Vampire Opportunist

The activation is the whole tell for when a 2/1 for two matters: the body chips in early, but the drain is a mana sink built for the deep late game, when a board stall has left you with lands and nowhere else to point them. Seven total mana to drain two and gain two (a four-point swing in a one-on-one game) is deliberately expensive, and the ability leaving the creature untapped is what forces the tax to be that high; a cheap creature that could reach across the table for life at any price would be a genuine engine rather than a slow trickle, so the cost pins the payoff to a phase where you can afford to sink it and keep functioning. It belongs with the cheap black creatures whose value lives almost entirely in the second half of a game: a warm attacker on the second turn, a grinding, inevitable clock ten turns later. Nothing intricate is happening here. The appeal is a repeatable drain that converts flooded turns into life loss, no support required beyond enough lands to keep firing it.