Good to see this developing. As an FYI, I recommend checking the errata for the older MMs. For instance, astral devas and solars lost polymorph and gained change shape instead, and solars get power word stun 1/day instead of at will (it was listed under both). In fact, most creatures that had polymorph as an SLA lost it and (usually) gained alternate form or change shape in it's place.
Looking forward to seeing the completed work. I played a good variant malconvoker for a short campaign, so I'll see if I can find my notes for what summons worked well. I remember packs of mustevals being funny just for their magic missile spam, and packs of three-headed leskylors could drop some OK aoe-damage with their breath weapons.
