Ertha Jo, Frontier Mentor is a uncommon Legendary Creature — Kor Advisor card from Outlaws of Thunder Junction (OTJ), collector number 203. Current market price: $0.23 (foil $0.35), TCGplayer market prices via Scryfall.
When Ertha Jo enters, create a 1/1 red Mercenary creature token with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery." Whenever you activate an ability that targets a creature or player, copy that ability. You may choose new targets for the copy.