Benalish Knight-Counselor 
Creature — Human Knight
Enlist Whenever Benalish Knight-Counselor enlists a creature, you get a one-time boon with "When you cast a creature spell, that creature enters with a +1/+1 counter on it."
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyNOT LEGALvintageNOT LEGALcommanderNOT LEGAL