Nashi, Moon Sage's Scion

Ninjutsu here works as a delivery mechanism rather than a bargain. The activation runs a full mana above the hard-cast, and that premium buys certainty: returning an unblocked attacker to hand swaps in a body already tapped and attacking in a lane the defender declined to contest, so the combat-damage trigger fires the turn Nashi arrives rather than hoping for a clean swing next combat. Survive that first hit and the engine compounds, exiling the top card of every library on each connection thereafter. The theft itself carries a life clause that rewrites how you spend what you steal: a spell costs life equal to its mana value rather than its printed cost, which unshackles the effect from your colors and your untapped mana entirely (a five-drop from any opponent's deck for five life the turn you land damage). The clause is self-governing, since you cannot spend a life total you do not have. What ties the whole 3/2 frame together is a pair of old black instincts made to work in one motion: the inevitability of a Ninja engineered never to whiff, and the willingness to pay life for access black was never granted by the mana it holds.