Niv-Mizzet, the Firemind

The character whose name the Izzet guild wears, rendered as a closed loop you supply with fuel. The tap ability draws; drawing pings; the ping clears a blocker, a planeswalker, or a face, and you do it again next turn. What makes this design endure is that it does not hide its engine behind a build-around tax: the card-draw trigger fires on every draw, not just the ones it generates, so any second draw effect doubles the burn. The classic infinite combo runs the other direction: attach something that draws a card when Niv-Mizzet deals damage, like Curiosity, and the chain feeds itself: the draw trigger pings, the ping draws, that draw pings again, and the loop only stops when you decide to point the last point of damage at something that ends the game. That open-ended phrasing made the Firemind a magnet for designers refining the mono-engine dragon: later Niv-Mizzet printings would tighten the trigger or widen the payoff, but this one set the template that drawing a card and dealing damage are the same action. The flying 4/4 body matters less than the text below it, though it is enough to attack into stalled boards and survive a sweep aimed at the ground. The honest cost is the mana value and the gold colors: a six-drop in two of the most spell-hungry colors, vulnerable on the turn it lands, asking you to protect it for a turn before the value compounds.