Theros Beyond Death

Callaphe, Beloved of the Sea | Legendary Enchantment Creature | Demigod | Callaphe's power is equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.) Creatures and enchantments you control have "Spells your opponents cast that target this permanent cost {1} more to cast." | Zack Stella

Ichthyomorphosis | Enchantment | Aura | Enchant creature Enchanted creature loses all abilities and is a blue Fish with base power and toughness 0/1. | Campbell White

Naiad of Hidden Coves | Enchantment Creature | Nymph | As long as it's not your turn, spells you cast cost {1} less to cast. | Kieran Yanner

Wavebreak Hippocamp | Enchantment Creature | Horse Fish | Whenever you cast your first spell during each opponent's turn, draw a card. | Caio Monteiro