Mind Flayer

Control-magic effects have always lived on an awkward power curve: permanent theft is one of the most brutal things blue can do, so the color has usually paid for it in enchantment form (Control Magic, Mind Control), where a single answer to the aura clunks the whole plan back to the opponent. Stapling the steal to a body changes what the opponent has to answer. The theft lasts exactly as long as the Horror stays on the battlefield, which reframes the interaction from "kill the aura" to "kill the creature," and a 3/3 dies to far more things than an enchantment does: combat, burn, edicts, sacrifice effects, chump-into-a-bigger-body. That fragility is the tax. Remove the Mind Flayer and the stolen creature snaps home, so the plan is only ever as secure as your ability to protect a mid-sized body on a contested board. What it trades away in durability it buys back elsewhere: you get a creature and a stolen creature from one card, the enters trigger repeats across blink and recursion, and a Horror can attack, block, and carry its own value in a way an aura's host cannot. It is the control-magic archetype rebuilt around a creature's vulnerabilities rather than an aura's, and the flavor closes the loop cleanly: the psionic tyrant that seizes a mind holds it only for as long as it lives.