Dragon's Eye Sentry

A wall that bites back, but only against a specific slice of the curve. The pairing of Defender and first strike is one of white's cleaner deterrent designs at common: the Sentry cannot attack, but three toughness behind a first-strike blocker means most early creatures stall rather than push through. The crucial detail is that the first-strike point does lethal work only against attackers with exactly one toughness: a 2/1 or 3/1 throws itself onto the Sentry and dies before dealing damage, while the 1/3 walks away clean. Anything with two or more toughness eats the single point and swings back, and here the block splits into two outcomes. A 2/2 trades power the Sentry can absorb and both creatures survive, a true brick wall. But a 3/2 survives the first-strike damage and then lands its full three, killing the Sentry outright: the wall does not stop that attacker, it dies chump-style with a parting scratch. The toughness-over-power split is doing the structural work at the bottom of the curve, where fragile one- and two-drops are common, and first strike upgrades the block from a speed bump into a one-sided kill against those. There is no upside ability, no reach, no late-game plan: it holds the ground floor against small, fast starts and asks the aggressor to commit something bigger. That narrowness is the design, and it keeps a single white mana honestly priced for the time it buys and nothing past it.