Saheeli's Silverwing

The enter-the-battlefield trigger here gives you information and nothing else: a single look at the top of an opponent's library, with no way to reorder it, draw it, mill it, or turn what you learned into a mechanical edge. The knowledge is real (whether to hold up removal, whether the coming topdeck matters, whether the race is yours) but it resolves once and then the card goes back to being a 2/3 flyer. That body is the part carrying the design. A colorless artifact creature with flying asks nothing of your colors, which is precisely why the effect is priced so gently: the peek is decoration on an evasive blocker that trades up in the air and chips in on the ground, and the mana cost reflects a creature doing modest work rather than an information engine worth building around. This is the design template for chaff, colorless filler that rounds out an aggressive shell without demanding commitment, and the top-of-library look reads sharper on the card than it plays across a game. Set the peek aside and you are left with a four-mana two-power flyer, a rate the higher-powered formats moved past long ago.