Capricopian is a rare Creature — Goat Hydra card from Commander 2020 (C20), collector number 58. Current market price: $1.37, TCGplayer market prices via Scryfall.
This creature enters with X +1/+1 counters on it. {2}: Put a +1/+1 counter on this creature, then you may reselect which player this creature is attacking. Only the player this creature is attacking may activate this ability and only during the declare attackers step. (It can't attack its controller.)