It doesnt matter how tough the creature is
2 Bon Clay (Bentham) from the Extra Booster Memorial Collection [EB-01] if the player is going first or Eustass Kid from Awakening of the New Era [OP-05] if the player is going second
But right now, one such set is up for sale, and its honestly not as expensive as you might expect (yet)
There are tons of ways to properly consider split cards and Assure is the first one on this list that is best mentally compartmentalized as Assemble with a backup mode. In the same vein as cycling, Assure is something more akin to an effect that may come in handy from time to time, but it isnt the reason to be playing the card
The problem is, Morophon supports only one type at a time, so that means cutting some letters out of KLOS
These cards can also be useful to get your characters healthy again if you decide to use Four Dozen Eggs to defend the board