Domri, Chaos Bringer
Most Gruul mana producers just add a source and hope you have something to spend it on. This one folds the spend into riot, so the mana ritual and the tempo swing happen in the same motion: point that mana at a creature and it arrives either as a bigger body or a threat that attacks now. That means the plus quietly protects its own loyalty by putting pressure on the board every turn you tick it up. The minus-three is the release valve for the archetype's chronic problem: aggressive creature decks flood on mana and starve on gas, and digging four deep for two creatures refills the hand without abandoning the plan. Between those two abilities the card asks almost nothing of the deck around it beyond "play creatures," which is the constraint that keeps it honest: it does nothing for a control shell and everything for a curve of bodies. The ultimate is the least interesting part, a token-engine emblem that rewards a board you probably already have. What distinguishes it from the value-walker template is that it never sits still to accumulate: starting at five loyalty gives it the cushion to spend aggressively rather than defend, and the mana wants to be spent the turn it resolves. The whole design is built to snowball a creature deck, not to survive in a vacuum.
Rules text
or . If that mana is spent on a creature spell, it gains riot. (It enters with your choice of a +1/+1 counter or haste.)
−3: Look at the top four cards of your library. You may reveal up to two creature cards from among them and put them into your hand. Put the rest on the bottom of your library in a random order.
−8: You get an emblem with "At the beginning of each end step, create a 4/4 red and green Beast creature token with trample."