Leonin Vanguard
Creature — Cat Soldier
At the beginning of combat on your turn, if you control three or more creatures, this creature gets +1/+1 until end of turn and you gain 1 life.
The best fighters are skilled in both harming and healing.
Aaron Miller
Core Set 2019 (M19)
• #22Rulings
If you don't control three or more creatures as Leonin Vanguard's ability resolves, the ability does nothing. However, if you do control three or more creatures as it resolves, the +1/+1 bonus doesn't stop applying if you no longer control three creatures later in the turn.
(wotc • 2018-07-13)
If you don't control three or more creatures as your combat phase begins, Leonin Vanguard's ability won't trigger at all. Causing a permanent to become a creature during the beginning of combat step won't cause Leonin Vanguard's ability to trigger.
(wotc • 2018-07-13)
Rulings
If you don't control three or more creatures as Leonin Vanguard's ability resolves, the ability does nothing. However, if you do control three or more creatures as it resolves, the +1/+1 bonus doesn't stop applying if you no longer control three creatures later in the turn.
(wotc • 2018-07-13)
If you don't control three or more creatures as your combat phase begins, Leonin Vanguard's ability won't trigger at all. Causing a permanent to become a creature during the beginning of combat step won't cause Leonin Vanguard's ability to trigger.
(wotc • 2018-07-13)