Your search for "agate instigator 56" revealed the following:
Agate Instigator (BLC) from Bloomburrow Commander, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: Quintin Gleim Card Text:Offspring 1R (You may pay an additional 1R as you cast this spell. If you do, when this creature enters, create...
Agate Instigator - Extended Art (BLC) from Bloomburrow Commander, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: Quintin Gleim Card Text:Offspring 1RWhenever another creature you control enters, this creature deals 1 damage to each opponent.
Agate Instigator // Rabbit Token (TBLC) from Bloomburrow Commander, available at 401 Games Canada. Rarity: Token Finish: Normal Card Text:Agate InstigatorWhenever another creature you control enters, this creature deals 1 damage to each opponent.(This token's mana cost is 1R.)