Once Stampede Rider’s ability has given it +1/+1, it won’t lose that bonus if you no longer control a creature with power 4 or greater later in the turn.
24-01-2020
wotc
If you don’t control a creature with power 4 or greater as your combat phase begins, Stampede Rider’s ability doesn’t trigger. If you don’t control one as the ability resolves, it has no effect. It doesn’t have to be the same creature at both times, however.
24-01-2020
wotc
Stampede Rider gets only +1/+1 from its ability, no matter how many creatures with power 4 or greater you control beyond the first.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.