The Countering Runner is a rare Legendary Creature — Merfolk Gamer card from Unknown Event (UNK), collector number RU05b. Current market price: $28.00, TCGplayer market prices via Scryfall.
Spells you cast that would counter a spell cost {U}{U} less to cast. Whenever a spell an opponent controls is countered by a spell or ability you control, draw a card. The Countering Runner deals 2 psychic damage to that player. (Psychic damage doesn't cause loss of life, but a player who's been dealt 20 psychic damage loses the game.) Ready to run (You can have two commanders if both have ready to run.)