Vesperlark

The evoke cost is the whole engine here: for you get a flying body that immediately sacrifices itself, converting a modest 2/1 into a reanimation trigger for the smallest creatures in your graveyard. The power-1-or-less clause is the leash, and it is a sharp one: it narrows the target pool to mana dorks, one-drop hatebears, aristocrat fodder, and the many one-power engine creatures whose value lives in their enters-the-battlefield or leaves-the-battlefield work rather than their combat stats. Reveillark does the same structural job at the top of the curve, returning power-2-or-less creatures when it leaves; this pushes the idea down the curve, tightens it by a point of power, then hands it an evoke discount so you can pay the leaves-the-battlefield tax on purpose. That last detail is why the fragile flyer earns its keep. Because the trigger fires on leaving the battlefield rather than on death, it interacts with removal differently than a die trigger would, and evoke lets you spend it at will instead of waiting for combat or a blocker to do the killing. Pair it with a creature that itself returns cheap creatures and the loop writes itself; the design assumes you will find the second half. The body is almost beside the point. You are buying a two-mana reanimation trigger with a built-in delivery mechanism.