2 Karumonix, The Rat King Toxic Rats While Karumonix, the Rat King, is a solid commander in its own right, it's much better used in the 99 since other commanders can make Rats quickly that Karumonix can back up
Now, Im gonna be listing specifically cards that have the prowess keyword ability and what other abilities or utilities they have that make them stand out
However, the activated ability on the creature half is most likely being underrated, as it does exactly what this deck wants and could let you trigger your key cards twice per turn cycle in the late game
For instance: A deck with a commander that costs two mana may avoid 2mv ramp because it anticipates playing its commander on turn two instead of ramping
Dredge 5 (If you would draw a card, you may mill five cards instead
Thats the key difference between mythics and lower rarities