Sleeper Agent

The joke is in the gift: a 3/3 body for a single black mana, an absurd rate for the era, handed straight to an opponent the moment it lands. The poison comes wired into the same card. This is donate-as-design, the engine running through Donate and Illusions of Grandeur and the whole "give your opponent something terrible" tradition, except here the curse rides along inside one spell rather than being smuggled in from a second piece. The strategic axis is a creature that doubles as a slow life-drain you have inflicted on the table across the way: the opponent gains control of a 3/3 and inherits a 2-per-turn upkeep tax they take, not you. That inversion is the whole point. You want the drain to keep running, which means you want the body to sit there bleeding its controller; the catch is that while it sits, it is also a 3/3 attacking into you, since they control it. So the opponent's out is to remove their own liability: kill it, bounce it back to you (you remain its owner, so it returns to your hand), or otherwise switch off the bleed, accepting the loss of a 3/3 attacker to stop paying two a turn. The rate has to be tempting enough that they hesitate to dispatch a free 3/3, and punishing enough that letting it ride costs them. Phyrexian flavor does the rest: the agent infiltrates, looks like an asset, and quietly poisons the host.