Hi,
I have an idea (well borrowed from other survival games)
In Completionist add another tab which rewards a perk
For killing a certain number of creatures.
E.g kill 500 prag beetles = prag nodes have chance to drop 3 prag instead of 2
Kill 500 fire lizard = 5 % damage increase
Kill X amount of Scorpion = improved base armor
Kill X amount of cloaked lizard = improve HP
Kill X queens = better life regen
E.T.C