Doors of Durin

An attack trigger that pays out before combat resolves rather than after, which is the whole reason it works. Scry 2 fixes the top card, then the reveal cashes it in: if it's a creature, it enters tapped and attacking, joining the swing that just triggered the artifact. The sequencing matters because the scry is not decoration; it lets you dig toward the creature you want to flip while pushing chaff and lands to the bottom, since a revealed noncreature card simply stays put and the trigger fizzles. The two conditional keywords are where the tribal seam shows. Dwarves grant the revealed attacker trample, so the free body isn't chump-blocked into irrelevance; Elves grant hexproof, so it survives removal aimed at the fresh threat. Both bonuses last until your next turn, which quietly protects the creature through your opponent's turn as well as the combat step it arrived in. Red-green has a long habit of turning attacks into card advantage, from cascade to impulse-draw to combat-trigger engines, but most of those hand you a spell or a card in hand. This one skips the hand entirely and deploys the payoff mid-combat, so the value and the board pressure land in the same window. The engine sits idle on any turn you decline to swing, tying its output to aggression rather than to accumulating resources: it repays commitment to combat, not patience.