How about class-specific creations?
For example,
shaper: shaping skills that alters / modifies existing, natural creatures(provided there are a lot of natural creatures in G4), making them vicious killing machines. / or the power to combine existing creatures to make something more powerful (a la impossible creatures)
guardian: creations that can be combined with armor, sword, helmet... , making the weapon/armor better, grants special abilities, but which slowly drains your essence or health. also, as someone said earlier in this pole, something that can be ridden.
scout(...or whatever the last class is called): small, incredibly fast and mindless creations that follows you everywhere and make you invisible / faster / venomous / submersible / gives special attack option.
Also, what if creations can be upgraded as they level up? If fyora's level goes over 10, then it becomes flamora(I know the name sounds stupid...) which is much bigger than fyora, can fly, can't be attacked by melee creations, can cast area-effect fire magic spells, etc.