Legion Warboss is a rare Creature — Goblin Soldier card from Ravnica Remastered (RVR), collector number 337. Current market price: $0.43 (foil $0.77), TCGplayer market prices via Scryfall.
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.) At the beginning of combat on your turn, create a 1/1 red Goblin creature token. That token gains haste until end of turn and attacks this combat if able.