Deeproot Waters - Ixalan - 51

Enchantment

Mana Cost: {2}{U}

Whenever you cast a Merfolk spell, create a 1/1 blue Merfolk creature token with hexproof. (A creature with hexproof can't be the target of spells or abilities your opponents control.)

Uncommon · Ixalan · #51 (XLN)

Illustrated by Zezhou Chen