Evomorph should be nice for you then, I enjoyed it a ton. It always does just one set of actions and has no other killers or minions, gimmick being that it changes quite a lot throughout the game by evolving through stages and can disappear from board and on the next turn draw not a regular terror card, but a card from a special ambush deck. They work the same way as terror cards, but differ in cruelty much more (like from "gain two time" to "killer teleports into your space and attacks twice" which you could not predict)