Grafter artificer ideas?

I'm making an artificer subclass for an upcoming Dnd campaign I'm running and need some help.

For context, the subclass is called Grafter and is all about using creature parts for attacks. I decided I wanted it to be an "options" type of subclass (i.e.. battle master fighter) where you can pick different creature types for different attack moves. I already have the mechanics for how it will work down, but i have no idea what to do for some creature types. Some creature types are unlocked at a later level so they will be more powerful, but i don't know what to make for each of them to make them unique instead of having it be "here's the same attack with a different damage type" 15 times. 

I'm still kinda new at posting on these forums, so i don't know if i can post pictures here, but if i can, I'll put something here about how the grafting mechanic works.