Yavimaya Gnats

A 0/1 flyer that spends green mana to shrug off a block exists to annoy, not to threaten. It deals no damage of consequence; what it does is chump an attacker in the air every turn, then regenerate for a single green and come back to do it again next combat. The regeneration shield is the entire point, and the body is just the delivery system for a recurring, mana-taxed wall above the ground. Early Magic was happy to give evasion and resilience to a creature with zero offensive ambition, treating both as defensive tools rather than the finisher-grade keywords they later became. The math here is deliberately small: one green per regeneration is cheap enough to keep doing it indefinitely, but it still demands you leave mana untapped, so the card quietly drains your tempo even as it preserves its own. It earns its slot by refusing to die, with no expectation that it ever accomplish anything beyond that, a defensive irritant trading your attention and your floating mana for one more turn of survival.