Horrid Vigor

Two keywords on one target, and the interplay between them is the whole design. Deathtouch means any amount of damage is lethal, so the creature you point this at kills whatever it fights: your one-drop trades with their bomb. Indestructible means it survives the exchange, because deathtouch does its work through "lethal damage," exactly the destruction that indestructibility ignores. So the pointed creature eats what it touches and walks away, a two-mana instant that flips a lopsided combat the other direction. The window is the catch: it lasts only until end of turn, which makes this a combat spell first and an ambush against a targeted removal spell second (it dodges destruction, though not exile or a toughness-reduction sweep). Green rarely gets a clean trick that reads this much like removal; its closest relatives are the pump-plus-protection spells that ask you to guess the block and win the math, and this asks less, because deathtouch means the numbers barely matter. What it does not do is anticipate. Cast it before blocks and the opponent simply declines the trade, and even at its best it is a one-for-one: you spend the trick, they lose a creature. The upside is in the leverage, not the card count: it lets a small creature answer something several times its size, and it turns their attempt to trade or profitably block into a losing proposition. Hold it for the right step, and it punishes a commitment the opponent has already made.