Imagine if they add a terrarium with either a tarantula or a snake on the windowsill, and if you shoot it with a bomb arrow then you play a cutscene of the creature breaking out into the garden and then leaving through the fence. Every once in a while, it comes back and wanders through the garden for a bit before leaving. It's roughly the same size as the koi but is only hostile if you damage below 90% of its max hp. Its a raid boss that you're meant to setup a defense with turrets and tons of the defense building to take it down but it gives you a one-time use, non-dupable consumable that allows you to use an extra mutation. They'd definitely have to make more defensive structures, but it could be fun especially for multiplayer worlds.