Scornful Aether-Lich

A blue creature by the only measure that counts (its mana cost) that nonetheless does nothing for itself until you have white and black mana on tap, and that split is the whole point. The 2/4 body is a fine wall and an inert attacker, serviceable on defense and pointless swinging into anything its own size. To earn its keep it spends a white and a black pip to pick up fear and vigilance for the turn, becoming unblockable except by artifacts or black creatures while never having to tap out of its blocking duties. The activation is binary, not cumulative: one payment grants the full package, and spending again the same turn buys nothing, so the card wants exactly enough off-color mana to flip the switch once per combat, not a hoard to feed. That makes it a deliberate allied-shard signpost, a card whose color is blue and whose color requirement to function is anything but, designed to reward a three-color WUB manabase that can actually produce those pips on demand. Fear plus vigilance is a durable pairing because it lets a body poke in for damage every turn while holding the fort, and bolting that combination to an off-color activation is the friction that justifies the rate on a creature that would otherwise just sit and trade blows. The artifact Zombie Wizard typing brushes a few type-matters axes, but the load-bearing idea is the gap between what color the card is and what colors it needs.