Mindmelter

An unblockable 2/2 that repeatedly picks at an opponent's hand should read as a menace, but the exile ability answers to a price only a purpose-built deck can pay: the activation demands colorless mana, the kind of production that never shows up in a manabase unless someone put it there deliberately. That gating is the whole balancing act. Without dedicated colorless sources the ability fires almost never; with them, the body grinds a hand down turn after turn. And exiling from hand is sharper than discard, because a card sent to exile never lands in the graveyard, so it slips past the whole family of triggers that key off a card being discarded specifically rather than merely spent. The unblockable clause earns its place less for two points of damage than for the survival math: a creature that cannot be blocked cannot be traded in combat, so the engine keeps ticking as long as the body lives. Devoid pushes the design further outside ordinary classification: it costs blue and black mana but carries no color, so removal and protection that key off either casting color slide off it entirely. The result is a payoff you assemble rather than a card you slot in. Warp the mana base toward colorless sources and it converts that commitment into slow, inevitable hand denial. Strip that support away and it reverts to an evasive 2/2 with an ability it cannot afford to use.