Any spell that requires an attack roll or any effect that offers a Strength or Dexterity saving throw can be used to affect objects as well as creatures. Objects automatically fail the saving throw against those effects.

Most objects are immune to poison and psychic damage, as well as all conditions. An object affixed to a surface, such as a door or tree, cannot be moved or teleported unless it is first unaffixed.

Large-sized PC’s can share the same space as allies that are medium-sized or smaller. 

A creature can choose to fail a saving throw for any reason, even if that creature is being controlled against their will. 

When an attack or spell that deals damage and has a secondary effect, such as knocking the target Prone or Dazing them, has its damage reduced to 0, either through immunity or other means, the secondary effect does not apply.

For example, if a creature immune to Bludgeoning damage is hit by a Mace with the Cripple Mastery Property, they do not suffer the effects, and if a creature Immune to Cold damage is subjected to the Rime’s Binding Ice spell, its movement speed is not reduced.

A creature that falls takes 1 die of Bludgeoning damage at the end of the fall for every 10 feet it fell, to a maximum of 20 dice. These dice are determined by the creature’s size, as shown below. When the creature lands, it has the Prone condition unless it avoids taking any damage from the fall. 

Small or Smaller - d4s

Medium - d6s

Large - d8s

Huge - d10s

Gargantuan - d12s

A creature that falls into water or another liquid can use its Reaction to make a DC 15 Strength (Athletics) or Dexterity (Acrobatics) check to hit the surface head or feet first. On a successful check, any damage resulting from the fall is halved.

Rate of Falling

When you fall from a great height, you instantly descend up to 500 feet. If you’re still falling on your next turn, you descend up to 500 feet at the end of that turn. This process continues until the fall ends, either because you hit the ground or the fall is otherwise halted.

Flying Creatures

A flying creature in flight falls if it is knocked prone, if its speed is reduced to 0 feet, or if it otherwise loses the ability to move, unless it can hover or it is being held aloft by magic, such as the fly spell.

If a creature with flying speed is knocked prone or otherwise loses its flying speed and falls as a result, subtract the creature’s original flying speed from the distance it fell before calculating falling damage.

A flying creature can choose to dive straight down, falling any distance it chooses before pulling up. This dive counts as falling and does not use the creature’s movement.

Falling Onto Another Creature 

If a creature falls into the space of a second creature and neither of them is Tiny, the second creature must succeed on a DC 16 Dexterity saving throw or be impacted by the falling creature, and any damage resulting from the fall is divided evenly between them. 

If one creature lands on multiple others, each impacted creature must make this save. Half the fall’s damage is applied to any creature that fails.

The impacted creature is also knocked prone, unless it is two or more sizes larger than the falling creature.

If the falling creature is 2 or more sizes larger than the impacted creature, the normal damage is dealt to both creatures instead of being halved.

When a medium or smaller creature grows to be large or larger, they choose what new spaces to occupy, one of them must be the space they occupied prior. When a creature shrinks from large or larger, they choose which of their spaces they now occupy. If this causes them to leave a creature’s reach, it ends any grapple that creature had on it and does not provoke an opportunity attack. 

• An Invisible creature becomes hidden to any creatures whose passive perception is lower than the creature’s passive stealth score (10+Stealth Bonus) until they attack, cause a harmful effect, or use the Magic Action. If an invisible creature that has been located moves or teleports, it becomes hidden again in the same manner. Any creature that tries to actively perceive an invisible target does so at disadvantage against the passive stealth score of the target.

• An invisible creature is heavily obscured.

• If a creature has special senses such as Blindsight or Truesight, it automatically locates any Invisible creatures within the area of that sense that are not otherwise hidden, and the creature does not count as heavily obscured.

Any action used to cast a spell, activate a magic item or use a magical effect such as a Clerics Chanel Divinity, A Warlock activating a Wand of Fear, or a Wizard slinging a Fireball counts as a Magic Action. If you take multiple Actions in one turn, you may only use one of them to perform a Magic Action.

A creature cannot willingly end their movement in a space occupied by another creature of the same size. a creature can end its movement in the space of any creature 2 or more sizes larger or smaller than it. If it is medium, it can end its movement in a space occupied by a friendly creature that is Large.

A creature can be pushed, thrown, or otherwise forced to move into the space of another creature regardless of size.

If you start or end your turn in the space of another creature that you can not move into the space of, you are shunted to an unoccupied space of your choice within 5ft of that creature, if possible. This movement does not provoke opportunity attacks.

Special creatures such as Swarms and Water Elementals can occupy the spaces of other creatures without being shunted, and creatures in their space do not get shunted out.

If a creature has an ally diagonally adjacent to it, they can choose to prevent creatures from passing in between them.

If a creature has access to multiple attacks with different reaches, each is considered separately for opportunity attacks.

Mounting. Once during your move, you can mount a creature that is within 5 feet of you or dismount. Doing so costs an amount of movement equal to half your speed. For example, if your speed is 30 feet, you must spend 15 feet of movement to mount a horse. Therefore, you can’t mount it if you don’t have 15 feet of movement left or if your speed is 0. 

To count as a mount, the creature must be at least one size larger than you and have anatomy that supports being mounted. If the creature is one size larger than you, you count as occupying all of its spaces while mounted. A mount cannot bear more than one creature that is less than 2 sizes smaller than it in combat.

Controlling a Mount. The initiative of a Mount changes to match yours when you mount it. It moves as you direct it, and it takes its turn at the same time as you. Bearing a rider puts no restrictions on the actions the mount can take. A controlled mount can move and act even on the turn that you mount it. The Mount’s movement doesn't count as your own.

Uncontrolled Mounts. When a creature has sufficient autonomy, such as a Dragon or an Awakened animal, they can act as an uncontrolled mount. The mount can use its movement on its rider’s turn, expending movement for its turn for every foot moved on its rider’s turn. Player characters that are mounted always act as Uncontrolled Mounts.

Falling off a Mount. If an effect moves your mount against its will while you’re on it, you must succeed on a DC 10 Dexterity saving throw or fall off the mount, landing prone in a space within 5 feet of it. If you’re knocked prone while mounted, you must make the same saving throw. 

If your mount is knocked prone or dies, you can use your reaction to dismount it as it falls and land on your feet. Otherwise, you are dismounted and fall prone in a space within 5 feet it.

A given area might be lightly or heavily obscured.

In a lightly obscured area, such as dim light, patchy fog, or moderate foliage, creatures have disadvantage on Wisdom (Perception) checks that rely on sight.

A heavily obscured area, such as darkness, opaque fog, or dense foliage, blocks vision entirely. A creature effectively suffers from the blinded condition when trying to see something in that area. When a creature is unseen, they count as heavily obscured to you. If two creatures are heavily obscured to each other, they do not gain advantage on attacks against one another.

The presence or absence of light in an environment creates three categories of illumination: bright light, dim light, and darkness.

Bright light lets most creatures see normally. Even gloomy days provide bright light, as do torches, lanterns, fires, and other sources of illumination within a specific radius.

Dim light creates a lightly obscured area. An area of dim light is usually a boundary between a source of bright light, such as a torch, and surrounding darkness. The soft light of twilight and dawn also counts as dim light. A particularly brilliant full moon might bathe the land in dim light.

Darkness creates a heavily obscured area. Characters face darkness outdoors at night (even most moonlit nights), within the confines of an unlit dungeon or a subterranean vault, or in an area of magical darkness.

Objects that are being worn or carried cannot be targeted by harmful effects. 

If a creature with Resistance or Immunity to a damage type gains vulnerability to that type of damage, it instead reduces Immunity to Resistance, or Resistance to normal.

When drawing a line of sight, start on one creature’s corner and draw a line to the corners of another creature’s space. If you can draw an unobstructed line to at least one corner of that creature’s space, then the creature is within sight. 

If one or more of the corners are blocked by cover, then the creature has half cover. If three corners are blocked, the creature has three-quarters cover. If all corners are blocked, the creature has full cover.

When targeting a larger creature, you only need to draw line of sight to the least obscured space that the creature is occupying.

For spells and other effects that affect an area, the area must overlap at least 2 corners on a single space that a creature or object is occupying for it to be affected.

A band of adventurers sneaks up on a bandit camp, springing from the trees to attack them. A gelatinous cube glides down a dungeon passage, unnoticed by the adventurers until the cube engulfs one of them. In these situations, one side of the battle gains Surprise over the other. 

The DM determines who might be Surprised. If neither side tries to be stealthy, they automatically notice each other. Otherwise, the DM compares the Dexterity (Stealth) checks of anyone hiding if it's a Player Character, or the passive Dexterity (Stealth) of any Non Player Character with the passive Wisdom (Perception) score of each creature on the opposing side. Any character or monster that doesn’t notice a threat is Surprised at the start of the encounter. Any hidden creatures are revealed as they launch the ambush.

Some effects state that they trigger when a creature enters a specified area. If such an area is moved into a creature's space, the effect does not trigger.

At the start of a creature’s turn, they may choose what items they are wielding. When a creature takes the Attack Action on their turn, they may draw, drop, or stow the weapon used for the attack as part of that Action. 

Grapple Save DC. Your Grapple Save DC is calculated as follows: 

Grapple Save DC = 8 + your proficiency bonus + your Strength modifier.

Initiating a Grapple. When you want to grab a creature or wrestle with it, you can use the Attack action to make a special melee attack, a grapple. The target of your grapple must be no more than one size larger than you and must be within your reach. Using at least one free hand, you try to seize the target by forcing the target to make a Strength or Dexterity saving throw (their choice). 

The target automatically fails if they are incapacitated. If they fail, you subject the target to the grappled condition. The condition specifies the things that end it, and you can release the target whenever you like (no action required). 

Escaping a Grapple. A grappled creature can use its action to escape. To do so, it must succeed on a Strength or Dexterity saving throw. If either of the creatures in the grapple is moved so that the grappled creature is outside of the grappling creature’s reach, the grapple is broken.

Moving a Grappled Creature. When you move, you can drag or carry the grappled creature with you, but your speed is halved, unless the creature is two or more sizes smaller than you. You can use your movement to move a grappled creature that is within your reach to any other unoccupied space within your reach, dragging it through the spaces in between.

Attacking a Grappling Creature. When a creature with extended reach grapples you, it can be targeted with melee attacks and touch spells as if it were in your space.

Climbing a Larger Creature. A opponent that is 2 or more sizes larger can be treated as terrain for the purpose of jumping onto its back or clinging to a limb. The smaller creature uses its action to force the larger creature to make a Dexterity saving throw, on a failure the smaller creature successfully moves into the target creature’s space and clings to its body. While in the target’s space, the smaller creature moves with the target.

The smaller creature can move around within the larger creature’s space, treating the space as difficult terrain. The larger creature can dislodge the smaller creature as an action—knocking it off, scraping it against a wall, or grabbing and throwing it—by making a Strength or Dexterity saving throw (it’s choice). On a success, the smaller creature is dislodged and is shunted to an unoccupied space of the larger creature’s choice within 5ft of that creature if possible.

Shoving a Creature. Whenever you use the attack action, you can replace it with a special attack to shove a creature, either to knock it prone or push it away from you.

The target must be no more than one size larger than you and must be within your reach. Instead of making an attack roll, the target makes a Strength or Dexterity Saving Throw against your Grapple Save DC. The target fails automatically if it is incapacitated. If the target fails, you either knock it prone or push it 5 feet away from you.

When a Player Character ties initiative with another creature, they always go first. If two or more player characters tie with each other, they decide the order amongst each other. 

Sometimes fate blesses or curses a combatant, causing the novice to hit and the veteran to miss. 

If the d20 roll for an attack is a 1, the attack misses regardless of any modifiers or the target’s AC. If the d20 roll for an attack is a 20, the attack hits regardless of any modifiers or the target’s AC, and it cannot be rerolled. This is called a critical hit.

When you score a critical hit, you get to roll extra dice for the attack’s damage against the target. Roll all of the attack’s damage dice twice and add them together. Then add any relevant modifiers as normal. To speed up play, you can roll all the damage dice at once.

For example, if you score a critical hit with a short sword, roll 2d6 for the damage, rather than 1d6, and then add your relevant ability modifier. If the attack involves other damage dice, such as from the rogue’s Sneak Attack feature, you roll those dice twice as well.

When looking to be unseen and unheard, you may use an Action to attempt to hide. Make a (Dexterity) Stealth roll, you are hidden from any creature whose passive perception is lower than the result of your check. If you can be seen by a creature and are not behind cover, then they automatically notice you. 

If you attempt to move stealthily, you can move up to half your speed and stay hidden as long as your movement doesn’t cause you to be visible or move out of cover. 

If you move more than half of your movement while hidden, make an attack, or take the Magic action, you are no longer hidden. If a creature becomes able to see you during your turn and you don’t have cover, you are no longer hidden from it at the end of your turn. 

When you finish a long rest, all spells that you have cast with a duration of less than 24 hours end. 

A spell fails if the caster attempts to target an invalid target. When a spell fails, the spell has no effect and the caster does not expend a spell slot. If a creature succeeds on the saving throw for a spell or is immune to a condition that the spell applies, it still consumes the spell slot even if the spell has no further effect on it. 

A spell fails if the caster attempts to target an invalid target. When a spell fails, the spell has no effect and the caster does not expend a spell slot. If a creature succeeds on the saving throw for a spell or is immune to a condition that the spell applies, it still consumes the spell slot even if the spell has no further effect on it. 

On your turn, you can only cast 1 spell of 1st level or higher across your Action and your Bonus Action. 

A duelist lunges for his opponent’s neck, a raging berserker swings his axe around his head before bringing it down with tremendous force. Whenever your character aims for a vital point or swings with all the momentum of their weapon, that is represented by them making a Power Attack. 

When you make an attack with a weapon in which you are Proficient, unless otherwise specified, you may choose to perform a Power Attack by removing your Proficiency Bonus from the attack roll to add twice your Proficiency Bonus to the damage roll. 

Shields - Now grant a +1 to Armor Class

At the start of your turn before moving or taking actions, you choose what weapons or shields you wield. When you make an attack you can draw or stow one weapon as part of that attack. Equipping or stowing a shield after the start of your turn costs an action.