Ertai, Wizard Adept

A repeatable Counterspell stapled to a fragile body, and the tension between those two halves is the whole design. Counterspell asks for two mana once; Ertai asks for four mana every time, plus a tap, plus a turn to survive summoning sickness, in exchange for never running out of counters as long as he sits on the table. That trade reframes the counter from a one-shot reaction into a tax the opponent has to pay attention to every turn: cast into open mana and an untapped Ertai, or wait. The catch is the 1/1 frame, which makes the card a magnet for any removal cheaper than the protection you'd have to hold up, and the activation cost itself locks four mana behind a sorcery-speed setup before it can do instant-speed work. The flavor matches the math: this is Ertai before his exile and corruption, the apprentice mage of the Weatherlight crew, a prodigy whose talent outruns his durability. Later printings would recast the character as a far nastier permission engine once the story had hardened him, but the original is the cleaner statement of the idea: permission you can repeat, if you can keep the wizard alive and the mana open.