Familiar - You can help pick!

[Wild Gazebo]

Imps have Alternate Form in 3.5 which acts like a polymorph (12lvl). They don't gain hit points from the change and can only assume one or two forms--no larger than medium size. I had a great (treacherous) imp familiar in 2nd Ed...course you used to gain a spellcasting level for an imp familiar then.