The Tavern

Hey, why should Vault Wardens get all the fun? And who is that running around making runed doorways all the time? Don't they realize that we can just walk past those without disturbing whatever's within? That seems like a terrible security system. It has to be Crawlers. An ancient magic, long lost, found again in the cliffnotes of some spellbooks people never read all the way through.

Seal Door: Level 6 Hexes spell
Found in the books of Cantrips and Enchantments, and possibly in randart books when the gods are feeling generous.

This spell's only valid target is a closed door or gateway. Unlike other spells the spell's casting time is always 1.5 turns (or longer as the case may be) as the spell must creep over and take hold of the door itself no matter how fast you think you can cast. And this spell can be interrupted by damage from any source, including poison. Upon casting, an effect will happen based on whether or not the spell was successful and the spell power of the caster. It doesn't work on staircases or portals.

Miscast- Upon miscast the player suffers a random Hexes miscast effect as normal, and the door in question either:
50%: Shatters into tiny pieces, forever destroyed.
50%: Emits a screeching noise in a 6x6 area, waking up anything nearby.

Upon success, depending on spellpower- higher power gives better chance of the better effects:
The door is temporarily sealed to all travelers, similar to the Vault Warden's version, for X turns.
The door is sealed with temporary red runes. These are breakable by the player like blue runes, but only last for X turns.
The door is permanently sealed with blue runes, as seen in vaults. These are breakable by the player as normal.

Well, this is a neat mechanic in the sense that there aren't many ways for the player to alter the layout of the dungeon (aside from closing doors in animals' faces, certain cards, and digging/disintegrating/shattering).

But as soon as you had spell power high enough to get blue runes reliably, optimal play would be to seal any door you don't immediately intend to walk through. That's tedious.

Cubicle of Dorokhle: creates a ring of doors around you

ftfy

More seriously this would be tedious as a spell, but a Scroll of Sealing could maybe work.

FR: Sil's Staff of Imprisonment and Staff of Freedom

Is it time to dig up the old Doorgod proposals from the devwiki...?

Can absolutely nothing open a sealed door? Thats pretty broken, especially making permanent ones. Admittedly the spell loses some of its use if its not permanent, but then you could just seal off every dangerous thing you find and they'll never get another chance at you (not until you're 5 levels stronger and got their weakness covered). Scrolls would probably be ok since you won't be able to spam them infinitely.

It might be best to remove the permaseal option -- the spell could give a temporary seal to a door in melee range for a duration dependent on spellpower. Perhaps monsters could open the door if they beat it on MR.