Gonti, Canny Acquisitor

The original Gonti, Lord of Luxury built an identity out of stealing from opponents' libraries; this version turns that theft into an engine and a discount at once. The cost reduction is the clever part: it applies to spells you cast but don't own, which means the cards you steal off the top of enemy decks all come out a mana cheaper, and the second ability hands you a steady supply of them. Each player your creatures hit in combat has the top card of their library exiled face down for you to play, with mana of any type covering the cost, so the color-fixing that usually complicates a Sultai deck solves itself for exactly the cards this Gonti wants to cast. Each ability sets up the other: the combat trigger fills your exile with foreign spells, and the reduction makes casting them worth doing rather than a curiosity. A 5/5 body is enough to demand a block and enough to survive a swing back, which matters when the whole plan runs through connecting in combat. What holds it together is that the reward scales with reach: one attacker mines one library, a wide board mines every opponent at once, and the discount stays flat regardless. The Aetherborn Rogue keeps the flavor of a broker who profits from other people's plans, only now the profit compounds every time your creatures land a hit.