Knull

Any other card where you choose or have chosen a creature type now has symbiote chosen in addition to the other type.

All other creatures you control are symbiotes in addition to their other types. Symbiotes can equip {0} to other creatures.

Whenever a creature that an enemy controls dies, give all symbiotes you control +1/+1. (Symbiotes that are equipped still get +1/+1.)