Sapphire Leech

A blue creature that taxes your own blue spells reads like a contradiction, and that contradiction is the entire design. Sapphire Leech belongs to a small cycle of Invasion creatures that pay for an above-curve flying body by penalizing the very color casting them: every blue spell after the Leech costs an extra blue mana, the kind of self-imposed tax that makes the 2/2 evasive body suspiciously cheap. The intended home was never a dedicated blue deck, where the symmetry-breaking penalty would clog your own hand; it was a deck splashing a couple of Islands for fixing, or an aggressive shell that wanted a hard-to-block clock and cast few blue spells anyway. That reframing is the clever part: the drawback is steep in the abstract but approaches zero in the right build, so the card rewards playing against type. It sits in a lineage of creatures whose stats are subsidized by an anti-synergy with their own color, a design lever Wizards used through the Invasion block to push creature quality without simply printing strictly better bodies. The leech flavor lands cleanly here too: a thing that drains the resource it shares your colors with.