How would you do this?

[Throne12]

So I really like the idea of setting magical traps. And I always want to use glyph of warding. But with it casting time. It really hard to use most of the time. But I Realize glyph of warding is a touch spell. So you can sit back start casting it then send your familiar into BBEG room. It walks in delivers the spell with the spell option on it. The spell casted into it is a devil sommon spell. Then Watch the two attack each other. It best if you cast magic circle and sit in it untell after the fight or leoman's tinyhut.

[Arc_knight25]

There is a lot of set up for this.

First you need to find the BBEG and not tip off mooks and such. Then have the time to cast said spell. Then hope your familiar isn't caught before it can lay down the trap.

Now you say devil, but I do believe the only devil that can be conjured/summoned is with the Gate spell, which is 9th level so you would need to spend two ninth level spells to pull this off. And with Gate the creature isn't under your control and can do whatever it likes once it comes through.

A Wizard can really only conjure Elementals. The first conjure elementals is a 4th level spell. So you would need two level 4 spell slots for this to work. The elementals also need a verbal command to attack, or they just sit there till attacked.

I do like your forward thinking though, but just to many factors to make this viable.

[The_Jette]

There is a lot of set up for this.

First you need to find the BBEG and not tip off mooks and such. Then have the time to cast said spell. Then hope your familiar isn't caught before it can lay down the trap.

Now you say devil, but I do believe the only devil that can be conjured/summoned is with the Gate spell, which is 9th level so you would need to spend two ninth level spells to pull this off. And with Gate the creature isn't under your control and can do whatever it likes once it comes through.

A Wizard can really only conjure Elementals. The first conjure elementals is a 4th level spell. So you would need two level 4 spell slots for this to work. The elementals also need a verbal command to attack, or they just sit there till attacked.

I do like your forward thinking though, but just to many factors to make this viable.

You could cast Magic Mouth on a gold coin and hand it to the familiar so that once the elemental is summoned it repeats your words to attack <BBEG>. It depends on your DM whether or not they'd allow that to work, since it's your willpower that makes the controlled creatures attack, not just your voice. But, it could work.