D&D 5E Making a spell permanent and trigger activated?

[atanakar]

I'm preparing the lair of a major villain in my campaign. It's a manor. I want some of the objects to be trapped with spells. For exemple, the rug in the foyer would have Evard's Black Tentacles imbued in it and the trigger «anyone who steps on the 10'x10' center area of the rug» would spring the trap. How do you do that with 5e? I don't see any spells to program spells and make them permanent.

 

[DEFCON 1]

You don't need spells to make them permanent. You just decide "this rug has this spell trap in it" and you run it that way.

 

[LordEntrails]

You do it by saying it. 5E does not treat NPCs like PCs. Therefore NPCs can do things that PCs can't and their are not rules to define what they can and can not do.

 

[atanakar]

It confirms what I was thinking. Thank you.

 

[jgsugden]

For a PC, I'd treat a triggered trap like making an uncommon magic item, unless they can do it purely with existing spells. It would opperate once an hour as an uncommon item, or recharge instantly if a rare item. That would be the easiest thing to do.

 

[BlackSeed_Vash]

What @LordEntrails says is true.
Also, the spell Glyph of Warding (3rd level) does everything you want, but would need to be recast each time it was activated. The Ward lasts until triggered, dispelled, or destroyed/moved +11ft (in the case of an item).

 

[lall]

We once faced an enemy with incredible abilities. Found out later he was the recipient of a Wish spell gone right. So as a general rule, if no other explanation works, you can use Wish.

 

[the Jester]

BlackSeed_Vash has it right- you want glyph of warding for this, if you want to stick to the rules and not DM fiat.

 

[LordEntrails]

DM Fiat is part of the rules

Just look at most any WotC published adventure. Take for example the Vault in WDDH, or half of everything in DoMM. The regional effects in PotA. etc.

Yes, use thing like Glyph of Warding to give you great ideas, but don't limit your imagination to what has already been written. Yes you want to make it "fair", but their are no rules to limit "fun".

EDIT: Oh, note that their are some spells (i.e. Ceremony?) that do have rules that if they are cast daily for a year they become permanent.

 

[atanakar]

I just read that Circle of Teleportation can become permanent if cast every month, for a year, at the same place.