Tomb of Horrors Adventurer
Two of the most demanding mechanics ever stapled to one body: the initiative, with its dungeon-crawling and its constant exposure to combat, and a spell-doubler that scales off completing a dungeon. The synergy is the point. Entering the battlefield puts you on the Undercity track; venturing toward completion upgrades the second-spell copy into a double-copy, so the two halves feed each other rather than sitting side by side. The reason this behaves like a value machine is that the copy trigger reads "second spell each turn" and lets you choose new targets: the doubler cares about spell count, not spell power, so a cheap cantrip or a modest removal spell becomes twice (or three times) the effect for no extra mana. The strategic weight lives in how fragile the initiative is. It changes hands the moment a creature deals combat damage to whoever holds it, the same trigger the monarch runs on, so this whole payoff structure sits atop a designation any attacker can pull away. Losing it does not undo your progress: you stay in whatever Undercity room you reached and simply stop advancing on your upkeep until you regain the initiative or venture again by other means. Still, stalling the doubler is enough to blunt the card, which is why it wants to be built not around one big spell but around a stream of cheap ones cast behind a body you can actually defend.
