It's in DMG II yes, it's called a Spell Turret.
It has a strict round-by-round basis tactic.
It's designed like this:
1st-4th round, 1 spell per turn. All spells from the same list, same level, different schools.
5th repair 4d8+20 points of damage.
It's unclear if any summoned monsters needs to touch the turret for it to cast touch-range spells on it. Example in the book states:
Stoneskin is a touch-range spell as we all know.
This turret is kinda annoying to face, just as an reflection.
It keeps on popping out summons, buff them whilst blasting you with lightning bolts all the same.
CR is equal to 1+spell level.
So somehow the following trap is CR 10.
1st round: Disjunction.
2nd round: Wail of the Banshee.
3rd round: Mass Hold Monster.
4th round: Sphere of Ultimate Destruction.
5th round: Repair 4d8+20.
6th round: Disjunction.
repeat until death.