Jet Medallion, Bolass Citadel, draw spells, tutors, and black cards that lack colorless requirements in their mana costs tend to work best with Krrik, as they help you stretch your mana and card access into ridiculously explosive turns that can win you the game on the spot if your opponents dont have access to any interaction
Dark Ritual was only a common in Mercadian Masques, so while the base printing isn't too much, the foil version is one of the biggest chase cards in the set
4,000 won is worth about $3.75, so technically packs here are a little cheaper
It can't be blocked by creatures of that color this turn
The major downside to this card is if an opponent has lots of creatures in play, like from a token-based deck, you could be stuck with no creatures in play yourself and an army from the token player