In general, I think an MC power has a high hurdle to pass to be worth taking: you have to spend a feat. So it doesn't just have to be better than the class power you could have taken, it also has to be enough better to justify the feat you could have taken. Since most avengers are feat starved, I don't think many of these are actually worth taking. Mostly, I'm mentioning them for Hybrid classes, or eternal seeker, or campaigns with house rules that lower the cost (3 power swaps for one feat, or Feat Tax allowance that reduces the effective cost of a feat). Also, Eternal Seekers have a much lower cost, and so can choose replacement powers more easily.
The various Sigil powers require Con more than Int, as they buff an item rather than actually make an attack. But any attack powers you take will require Int, so make sure Int is at attack levels.
Slick Concoction (EPG,u10e)
Minor action re-arrange the battlefield encounter. Better with initiative, but really good regardless. At higher levels, you'll want to replace with Bag of Four Winds
Arcane Springboard (EPG,u2d)
Great mobility and flavor, but you've got some nice utility powers at this level too.
Corrosive Sigil (EPG,d5)
At will ongoing damage for an encounter. Nasty.
Dancing Weapon (EPG,d5)
Minor action attacks for an encounter. Nastier. If your DM allows you to get your oath (PHB2: "you make an attack through the creature") this is the bomb, even if you do have to keep a backup weapon for it to use, and a minor to move it around the board.
Vorpal Edge (EPG,u16d)
18+ is a really nice crit range, even if it is just for one encounter per day. Worth less if you already have a 19+ crit range.
Hellfire Sigil (EPG,d19)
This ought to buy you a couple round of oath, but save-ends typically drop working quickly, and your Con score isn't all that (a common problem with the otherwise great "Sigil" powers)
Bag of Four Winds(EPG,u22e)
Rearrange the battle field, as an encounter.
Chaos Weapon (EPG,e23)
If your party fights in a tight group, this ought to be a good lead in for a Nova round. But you'll never take this power, cause you'll take Prismatic Strike instead.
Prismatic Strike (EPG,e23)
Three damage rolls with some nasty effects, on one attack roll. Please make sure you use this power on the rounds you have the silly high static modifiers. Probably worth a feat.
The Mixed rating here is due to the cheese factor. If you read some of the powers literally, you have powers that are VERY interesting for avenger power swaps (based on a secondary stat), and are equivalent to some Barbarian and Ranger powers. If you read them as was more likely intended, you have powers that are horrifically bad for the role. So, Rating depends on the DM. If the DMs willing to go along, this is a good choice. If not, it's a pretty bad one. The second element has to do with "power source". The original Assassin class is a Shadow class, which has no support of any note whatsoever. The newer one is both Shadow (yawn) and Martial (er? Say what?). So ... what's the MC feat get you? I have no idea. If your DM thinks it gets you Martial , then Impaling Spear says "hello", and we've got an honest option to Fighter.
Ghost on the Rooftops(HoS, u6w)
If you want to jump or climb around like a real ninja, but don't have the Str, here's how. Jump/climb your speed as a move action, no qualifiers.
Flurry of Talons(D379, e13)
Read literally, a three tapper. (You hit? You do 1d8+Blah. You hit twice, you do a total of (1d8+Dex+Static + 2d8+Dex+Static) (3d8 + 2*Dex + 2*Static). Hit three times? 6d8+3*Blah.) And it's an approach power too. With good static modifiers and/or setup, this should let you one-round a standard. The downside is that it's an implement power.
Shadow Fire(D379, e17)
Read literally, another three tapper. Has the advantage of being a Weapon power (Manga-sized swords or Warshovels like that), but trades an approach aspect for a "run, cause you can't see me" aspect.
Claim the Dead(D379, u22e)
A "Transit after killing someone" power (which is usually good for a minor action attack, when used with Soul Forge Hammering )... but interestingly enough, it stacks with other transit, because it gives you a MOVE ACTION, not a move. So if you don't have transit, this gets you some. If you do, this gets you ANOTHER minor action attack next turn.
All the Barbarian powers are really just good for Crit Fishermen or other strength based builds.
Storm of Blades(PHB2,e13)
Up to three attacks as long as you don't miss? Sold?
Thunderfury Rage (PHB2,d15)
Free MBA each round, assuming you're attacked... which should be easy enough to ensure. Compare to Snarling Wolf Stance , depending on your flexibility in choosing powers.
Stone Tempest Rage (PHB2,d25)
Crit 18+ for an encounter. (And the initial damage isn't shabby either)
Hurricane of Blades(PHB2,e27)
Critfisher, does Eternal Seeker have your undivided attention now?
Many of the good cleric Wis-based melee powers come from Essentials ( Heroes of the Fallen Lands ). Some of them are useful to a striker, and the Tactical Warpriest Paragon Path is good for defender-lites. For non-weapon powers, I'm assuming builds that are Leader minors.
Lesser Aspect of Wrath(HotFL,d1)
+1 to hit is nice, and run-or-Con_Mod-auto-damage is nice, even if Con_Mod isn't so hot. Aspect of Might is good enough that this isn't worth a feat.
Bless(HotFL,u2d)
+1 to hit for a party. Nice, but not worth a swap.
Cure Light Wounds (PHB,u2d)
Surgeless Healing is always good. Standard action is bad, so this would mostly be for out-of-combat use.
Sanctuary (PHB,u2e)
More help moderating your defenses, but it's a standard action.
Divine Castigation(HotFL,d5)
A mark emulation that allows you to punish the target if it attacks you too. That ought to get it to run.
Spiritual Weapon (PHB,d5)
If you have a friend keeping the BBEG locked down, this gives you multiattack. If you don't, you'll rapidly have to decide between moving the conjured sword or yourself. Choose yourself, Implement Attacks vs. AC don't work well, and ranged attacks can't use your Oath.
Weapon of the Gods(HotFL,d5)
Minor action self-buff. +1d6 radiant damage for an encounter, and an AC debuff. No brainer for a hybrid, 'spensive for a feat.
Cure Serious Wounds (PHB,u6d)
Surgeless Healing is always good. Standard action is really really bad.
Divine Power (PHB,u6d)
Good buff, but it's a standard action. Blech.
Champion of the Gods(HotFL,d9)
Aspect of Might , minus the speed bonus and 1{W}, but a damage bonus that could be higher if you have a really good Con. Not worth having a really good con.
Mass Cure Wounds (PHB,u10d)
Surgeless Healing is always good. Standard action is always really bad. Comrad's Succor is usually good enough for out-of-combat healing.
Union of Three Fates (D380, e13)
Ok, some serious caveats here.
# You have an Implement, for some reason (weaplement? Ki-Focus?)
# You have good statics on Ranged Implement attacks. (Mage shard, but ... ??)
# You can guarentee an encounter hit with a ranged power (leader and a re-roll, dice, Oracle theme)
Then you have a triple-tap striker power that should have been on your class list to begin with. 1d10+Wis+Static, 1d10+static cold, 1d10+static necrotic. And an ally spends a healing surge: if that's still needed.
Divine Armor (PHB,u16d)
Good for chasers who want their target to get bored, but a standard action.
Knight of Glory (PHB,d19)
Fundamentally a higher level Spiritual Weapon.
You're here because you're a lycan looking at Blood Moon Stalker , and looking for options. Well, they're bleak on the encounter front. There are some daily buffs that might be worth the action cost though. The main issue with encounter powers here is one you'll face in Blood Moon Stalker too: Implements. Ki-Focus proficiency is out: your theme is spoken for. So it's 'keeping the Cleric's cast-offs', limiting your Expertise feats, and hoping the statics don't drop too far.
Heat Metal (HoFK, d1)
Level 10+ lycan's: It doesn't say "5 extra damage", it says "also takes 5 damage". That's a 2nd damage instance that (maybe, ask your DM) got attached to your melee power you just hit with (with CA). I think your claw gloves just kicked in again. Also: Inferno Oil is common, just so you know. And secondary attacks inherit keywords, so it's more accurate than you think. Downside: 1/rnd means it's not a multiplier. But be happy with your extra damage instance for this combat.
Claws of Retribution (PHB2, e13)
One OA-MBA? Should work.
Envenomed Steel (HoFK, d15)
See Heal Metal , except poison is very commonly resisted.
Stonemetal (HoFK, d15)
Same thing, less damage, more prone.
Storm Weapon (HoFK, d29)
Still 1/rnd, but now with Daze. (And lightning, which can turn into radiant, for more vuln tapping).
I've split the fighter powers into two seconds: powers good for any build with a 13 str, and powers that require attack-levels of strength. Obviously, the second category is bigger.
For any build:
Battle Fury Stance (D382,u2e)
+2/4/6 static damage, for -2 AC. This was broken-good when it was a weapon enhancement, making it a power doesn't hurt too much.
Rain of Steel (PHB,d5)
This will cause someone to run. And if not, will kill them much faster.
Martial Supremacy (D382,u22e)
MBA-spamming crit-fishers only, but OMGWTFBBQ for them. Twin strike levels of crit fishing without having to screw up your stats or change your preferred MC.
As with Battle Fury Stance , an encounter stance broken by spending a surge. But at level 22, your leader should either make sure the combats over before you get hit, or have enough surgeless healing handy that it's not too crucial either way.
Rain of Blows (PHB,e3)
Not as good after the July nerf, but still skyblue. If you can, bring a spear, flail, or light blade. But if not, it's still two attacks with a big weapon, and that's still good.
Chains of Sorrow (PHB,e13)
If you use a flail, and have managed to keep a decent dex, this is a debuff almost as potent as Armor Splinter. If you're looking at powers from Eternal Seeker, Armor Splinter is better.
Harrying Assault (MP,e17)
Multiattack and movement, without the TWF requirement.
Weaponmaster's Lure (MP,e23)
Multiattack, mobility, forced movement.
Reaper's Stance (PHB,d25)
If you've collected a large number of fighter powers (PMC much?) and kept a high Dex, this rocketh thy socksith . If not, it's a better Rain of Steel. Which still ain't bad.
Force the Battle (PHB,d29)
Only does insane things to Fighter powers, and only grants Fighter at will powers. Since Dual Strike no longer is a Twin Strike clone, not as handy as you'd hope.
Written in Fire (DP,e7)
If enemies don't get at least 6 squares away from one spot, they take 10+Wis_mod damage. That might get them running... suggest this to your Invoker, if you have one though, as it's probably not worth the cost.
Bless Weapon (DP,u2d)
By itself, may or may not add the radiant keyword (which Warlocks care about more than paladins). But you see that "Crit on 18+ against creatures vulnerable to radiant damage" bit there? Ring any bells, like, oh, say, Power of the Sun , or Punishing Radiance ?
Divine Vengeance (DP,d15)
Stance that hurts enemies that attack you or adjacent allies. Good for chasers who've taken the monster out to the woodshed.
The majority of Ranger powers are really just good for Crit Fishermen. As usual, my advice is really to only take these if they cost less for some reason. As a note, for many of the "Fishermen" powers, you can take Nerathan High Blade Duelist (it has a preq, so this is two feats on top of the MC and power swap) to make your power-swapped power run off of Dex. Its a lot of feats, but then you have a very interesting Nova power AND an AC.
For Chasers:
Snarling Wolf Stance (MP2,d5)
If you attack me, I get an MBA against you (and shift) as a reaction. Why don't you run instead... May be worth a feat for chasers.
Resume the Hunt(MP2,u10e)
After you drop your first target, get free transit to the 2nd. Will frequently save you a move action, letting you turn it into a minor action attack. (Mostly relevant for Soul Forge Hammering , where you'll typically have the ability to get a minor attack off in the next round, when the guy you used your standard on last round got killed by your allies. Suddenly you need to Oath, Transit, and still have a minor, which can get tricky.)
Tiger's Reflex (PHB,d25)
A stance which grants a melee basic if an enemy attacks you, as an immediate interrupt. Would replace Snarling Wolf Stance in chaser builds.
Long term, ending up with both Armor Splinter and Lashing Leaves isn't the worst fate in the world. Both have kickers than can be brutal, especially if you managed to pick up a higher count multi-attack (Blade Cascade? Hurricane of Blades?) somewhere along the line.
Off-Hand Strike (MP,e1)
Boring old off-action attack (off hand weapon).
Plant to the Hilt (D377,e1)
Multiattack + Slide. Better than just multiattack.
Two Fang Strike (PHB,e1)
Boring old multiattack. Prefer Plant to the Hilt
Jaws of the Wolf (PHB,d1)
Boring old multiattack.
Confusion of Blades (D377,e3)
Multiattack, but it rewards something you don't want to ever happen.
Ruffling Sting(MP,e3)
Boring old off-action attack (off hand weapon). Can be made to be based off of Dex.
Claws of the Griffon(PHB,e7)
Boring old multiattack. Can be made to be based off of Dex. As a note, there's a rules argument that each hit does ([1]W + Stat + Static + 2[W] + Stat + Static). This is an artifact from PHB1 ranger powers not being written according to the current rules, and is most likely not intended. But if your DM claims its a pure raw game, haul out the Rule Compendium, and have fun with your 4-tap power.
Lashing Leaves (D377,e7)
Multi-attack, plus one turn long HUGE vulnerability. Keep this for a while (Reserve Maneuver?)
Armor Splinter (PHB,e13)
A multi-attack that's tied to a spectacular AC debuf, which is a great setup for Blade Cascade or Hurricane of Blades.
Storm in the Trees (D377,e13)
Boring old multiattack with mobility. You have better options.
Off-Hand Diversion(MP,e13)
Boring old minor action attack (off hand weapon). Can be made to be based off of Dex.
Blade Cascade (PHB,d15)
Keep attacking until you miss (or 5 attacks)? Your sticht is that You Don't Miss.
Canopy of Blades (D377,e17)
Boring old multiattack with AC Buff. Good for Masters of Defense that are also playing around with Crit Fishing.
Master of the Hunt (PHB,u22d)
Even more reason to have your teammates give you attacks, even more reason to bring out multiattacks. Takes your stance slot, which means it competes for DPR with Follow-up Blow
Verdant Silence (D377,u22e)
Encounter Power is what makes it worthwhile. Spend a surge to end anything a save can end... except Stun. Because it's a Free Action, not a No-Action.
Avalanche of Fury(MP2,e23)
Multi-attack with a weird version of reliable. Can be made to be based off of Dex.
Crashing Blades(D377,e23)
Multi attack, with a possible Daze.
Cloak of Thorns (PHB,e23)
Multi attack, but the "attack me and I get melee basic as interrupt" is the real draw.
Nonchalant Collapse (MP,e23)
Boring old Weapon vs. Fort off-action attack (off hand weapon).
Death Rend(PHB,e27)
Multi-attack, with a "Stun" kicker. Can be based off of Dex. It's not clear which instance the bonus damage for hitting twice attaches to.
Seeking Roots (D377,e27)
Multi attack, with more Ws. If you have a silly high Crit Range (17+ or 18+), it's better because of the good odds you'll get even more Ws to maximize.
Follow-up Blow (PHB,d29)
Encounter long multi-attack. It used to add to Nova turns, now just adds to DPR.
The Rogue powers I mention all require Dexterity, except Raise the Stakes, so most of them are only suitable for Chasers and Ninjas.
Low Slash (MP,e3)
A minor action attack that's Weapon vs. Reflex. This works like multi-attack, in that you get more chances each round to apply your silly high damage bonuses when they are silly high... but Fury's Advance is in class and so doesn't require a feat.
Clever Riposte (PHB,d5)
Requires a light blade, but gives the target a large incentive to leave you alone. And since only 5th level, can be recharged with Slaves of Power.
Raise the Stakes (PHB,u16d)
Crit on 17+? Are you serious? Requires Bluff and only lasts two turns though, which is rather short for a daily. Combo with a multi-attack power for a nova turn. Skip if you've a Dagger Master though, as it's not enough of a change.
Dragon Tail Strike (PHB,d17)
Really for the chasers. Gives the target a LARGE incentive to leave you alone. Just make sure there's no one else he can attack without moving, and you'll either get a second attack this round, or bonuses next.
Perfect Strike (PHB,e27)
You have a class power that does 6W, so doing 5W here isn't all that. But you've got a very decent chance to stun. Which is.
Skirmishing Strike (MP,e27)
A minor action attack. But the difference between 1W and 3W isn't high, and shifting 1 isn't all that either, and it gives you a penalty to hit for some reason. Keep low slash (or Fury's Advance)
Assassin's Point (PHB,d29)
7W of a light blade isn't all that, and post the RRoT nerf the crit line becomes very conditional. (It isn't rolling extra damage on a crit, so RRoT doesn't trigger it)
The major problem with spell scars is their assumption that all weapon attacks should by physical, and all implement attacks should be mental. Most of you would rather make mental (Wisdom) based physical attacks (to get the censure). So the net effect is only Fishermen and Chasers have any interest in spellscar attack powers, because only they have physical attack-level stats.
Burning Blade (FRPG,d5)
A stance that applies 5 ongoing with two keywords, might cause someone to run, but probably not. It isn't a damage roll, so it won't scale at all.
Tears of Fire (FRPG,u10e)
Take damage to get +4 to an attack you just made. So should help you miss less once/encounter. But the damage it does scales quicker than the damage you do, so you'll want to get rid of it eventually.
Body, No Body (FRPG,u16e)
Phasing for a turn is all it's really good for. Insubstantial is usally something you want until your NEXT turn. (Downgraded one step because you have to take a feat to get something you have a class power for)
Gravity of Moment (FRPG,d19)
Ranged attack, but not a huge difference in net effect between missing and hitting. Either way, you get to slide the target around the battlefield like crazy for the rest of the battle. Best used on a Melee critter you'd rather not attack yet: just remember to keep a minor free to sustain it every turn.
Donning the Mudflesh (FRPG,u22d)
Insubstantial until bloodied. Some martyrs (those with regeneration that works when you're not bloodied) will really like this, and masters of defense also like this. Takes your stance slot.
Shifting Wave (FRPG,e27)
Re-arrange the battlefield as an encounter. Not as good for the martyr as Scatter to the Astral Winds (you have to hit the enemies you wish to move) but not horrible.
Metamorphosis of Spellflame (FRPG,d29)
Implement attack with a range of Melee Weapon. So yeah... Targets the lower NACD of Will or Fort, so it pretty accurate, especially for you. But it can be wasted (has no miss effect) and it's just save-ends damage. If you can get some orb-izard in there, it's a LOT of save ends damage, which is why it made the list.
Reach of the Doomed (FRPG,e7)
Gives reach, which you'll never use, because if you hit with the first attack, you get a second that also has a damage roll... aka. Multiattack. So you really want to hit with the first.
Venomous Bloodfant (FRPG,e7)
A small hit, but get some minor healing.
Iron Tooth of Bloodlust (FRPG,e17)
Venomous Bloodfang's 2W older brother.
Echoes of Valor (FRPG,d29)
Minor action attack does 5d10+stat until you miss. So multiattack for 5-6 rounds, likely, with a rather big stick. That doesn't suck...
Two things of note under Warlock: Ethereal Sidestep for mobility, or Eldritch Strike for MBA spamming half-elves
Eldritch Strike(PHH,1w)
The idea here is to go Student of Caiphon for the 18+ crit range, and spam an At-Will all day. Use Adept Dilletante to make Wis your attack stat, so that you have an armor class. Use White Lotus Master Riposte to either get Silly DPRz, or get your censure bonus on a regular basis. The alternate approach to Eldritch Strike abuse is to MC Fighter ( Draeven Maurader ), get all the usual MBA boosters, and then power swap for Martial Supremacy . Surprisingly charge with your Vanguard Warshovel, with 4 attack rolls each attack critting on an 19+. Hopefully things will die before they realize you have the AC of an unattended object. If Windrise Ports were still around, this would be spectacularly awesome, as you could do both. But it's not... so it's just two options for sillyness.
Ethereal Sidestep(PHH,u10w)
Teleport is the 2nd best movement mode, but teleport 1 isn't as useful as you'd like. If you pick this up, pick up some boosters.
Transcendent Dance (PHB,u10d)
Small bonus to speed and saves for an encounter.
Painful Transference (PHB,u16e)
Once an encounter, end one effect (no action), but do 2 points of damage to all teammates within 5 (assuming a starting 13 cha, for the MC feat(s)). Hopefully they'll forgive you.
Wakeman's Invocation (PHB,u22d)
One encounter a day, don't get hit by any melee attackers without reach. Well, they could gang up on you and run you out of immediate interrupts...