Is Valiant Batrider legal in Standard, Modern, and Commander?

Valiant Batrider is legal in: Historic.

Valiant Batrider

Q: What type of card is Valiant Batrider?

Valiant Batrider is a Creature — Human Knight. Its oracle text reads: "Flying Whenever Valiant Batrider deals combat damage to a player, that player gets a one-time boon with "When you cast a noncreature spell, you may pay {1}. If you don't, each opponent draws a card." Power/Toughness: 3/3"

Creature — Human Knight

Flying

Whenever Valiant Batrider deals combat damage to a player, that player gets a one-time boon with "When you cast a noncreature spell, you may pay . If you don't, each opponent draws a card."