Caves of Chaos Adventurer

The initiative mechanic bolted onto a body designed to abuse it. Entering the battlefield hands you the Undercity dungeon and its slow-drip advantage, but the attack trigger is where this card weaponizes the venture ecosystem: swing, exile the top card, and if you've already walked the dungeon to its end, play that card for free. It becomes a race against yourself. A 5/3 with trample wants to attack every turn, which is exactly the clock the initiative rewards, since holding the initiative advances your dungeon and the completed dungeon is what unlocks the free plays. Get there and every attack is an impulse draw you get to play for nothing, stapled to a creature you were swinging anyway. The catch is legible in the stat line: three toughness means this dies to most of what an opponent throws at it, and losing it before you finish the dungeon leaves you with a fair-rate impulse-draw beater rather than the free-spell engine. That fragility is what the power costs. The card promises a runaway advantage but demands you keep a five-power attacker alive through the exact window your opponent most wants it dead, and the initiative itself is a target painted on your board that anyone can steal by dealing combat damage to you.