Also all improved familiars are not that good (Complete Warrior introduces some more combative familiars, blind dog and winter wolf are nice until you realize they use your BAB in longer run of things). Imp's or quasits are more versatile and have lots magic bling to bring on the table. I like tressyms but statically they are crappy for improved familiars (they should be potential gained as normal familiars after certain level cap).<br/><br/>Besides that, there are some handy familiar spells like one which allows swap familiar and master's positions and also there is feat which allows familiar cast spells like their master does (up to 2th level when master is around +17th level). Not to mention if Adrian learns use magic devices, his imp can use wands and such through those means.