You create a magic seal that bears your visible arcane mark (and though you do not have to cast arcane mark to cast lesser arcane seal, it must be a spell you know). The seal you create resembles the wax seal one sees on letters and documents, and can range from 1 to 6 inches across.
A lesser arcane seal is exceedingly tough, having a hardness of 10, 30 hit points, and a break DC of 25. When placed on a door or other closure (a chest, window, and so forth), the lesser arcane seal grants the portal its break DC or adds +5 to the portal's existing break DC (whichever is higher). The seal is unaffected by knock spells unless the caster makes a caster level check (DC 12 + your caster level). A rogue or other character with the trapfinding class feature can break the seal with a DC 27 Disable Device check. At your option, you can also imbue the seal with magical energy so that any creature breaking it takes 1d8 points, plus 1 point per caster level (maximum +5), of acid, cold, electricity, fire, or sonic.
Each kind of damaging seal also has a particular effect:
• Acid: A lesser acid seal leaves a patch of acid on the victim if it fails a Reflex save, dealing 1 point of continuing acid damage each round for 1d4 rounds. The affected creature can make another Reflex save as a full-round action to neutralize the acid (assuming no other means to do so is available).
• Cold: A lesser cold seal slows the victim (as the spell) for 1d4 rounds on a failed save.
• Electricity: A lesser electricity seal leaves the dazed for 1 round on a failed save.
• Fire: A lesser fire seal leaves the victim dazzled for 1d4 rounds on a failed save.
• Sonic: A lesser sonic seal produces an audible wail for 1 round when broken, audible to anyone within 60 feet.
Reduce the distance by 10 feet for each interposing closed door and by 20 feet for each substantial interposing wall, then triple the result for quiet conditions (to a maximum of 180 feet). When you add a damaging effect to the seal, you must add additional runes to the seal. Anyone can read these runes and discover the seal's effect with a DC 12 Spellcraft check.
You can disable a lesser arcane seal simply by touching it and using a standard action to dismiss the spell. At the time you create the seal, you can specify a password or phrase that allows other creatures to break the seal with no difficulty, and without triggering any damaging effects.