Legion Warboss is a rare Creature — Goblin Soldier card from Guilds of Ravnica Promos (PGRN), collector number 109s. Current market price: — (foil $2.62), 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.