Your search for "Dauntless Onslaught 99" revealed the following:
Dauntless Onslaught (JMP) from Jumpstart, available at 401 Games Canada. Rarity: Uncommon Finish: Normal Artist: Peter Mohrbacher Card Text:Up to two target creatures each get +2/+2 until end of turn.
Dauntless Onslaught (DDN) from Duel Decks: Speed vs. Cunning, available at 401 Games Canada. Rarity: Uncommon Finish: Normal Artist: Peter Mohrbacher Card Text:Up to two target creatures each get +2/+2 until end of turn.
Dauntless Onslaught (DDO) from Duel Decks: Elspeth vs. Kiora, available at 401 Games Canada. Rarity: Uncommon Finish: Normal Artist: Peter Mohrbacher Card Text:Up to two target creatures each get +2/+2 until end of turn.
Dauntless Onslaught (J25) from Foundations Jumpstart, available at 401 Games Canada. Rarity: Uncommon Finish: Normal Artist: Jesper Ejsing Card Text:Up to two target creatures each get +2/+2 until end of turn.
Dauntless Onslaught (THS) from Theros, available at 401 Games Canada. Rarity: Uncommon Finish: Normal Artist: Peter Mohrbacher Card Text:Up to two target creatures each get +2/+2 until end of turn