Powerful Conjuration Spell (Really need help)

[Aeromyre]

A year ago in my characters first adventure, I made a villain with a powerful conjuration spell called "Basudra's Evil Twin" (This was AD&D)
We now Play Pathfinder and I want to bring Basudra back as the BBEG. I lost this spell and the players thought it was so great and wanted to have it.
Tell me what level you think it would be.

Basudra's Evil Twin
Will Save: Resists Temptation to attack twin
When cast upon a target an exact copy with all abilities, apears and the character will be mesmerized by his Evil Twin and will make a will save to resist not attacking it. Any Items with Good alignment will have an evil descriptor and if possible the evil version of the effect. If anyone wishes to attack the Evil twin or the Character there is a 50% Chance they will attack the wrong one. Who ever survives becomes that person whether it is the twin or not. If it is the twin who survives his new alignment is evil.

Also now that i don't have just one kind of spell caster type (Magic User) WHat is a good Spell Caster build for someone of around level 12?
Thanks guys