Marble Diamond

Marble Diamond enters tapped.
{T}: Add {W}.

Rapid Hybridization

Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.

Hindering Light

Counter target spell that targets you or a permanent you control.
Draw a card.

River's Rebuke

Return all nonland permanents target player controls to their owner's hand.

Sky Diamond

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.

Riptide Laboratory

{T}: Add {C}.
{1}{U}, {T}: Return target Wizard you control to its owner's hand.

Folk Hero

Commander creatures you own have "Whenever you cast a spell that shares a creature type with this creature, draw a card. This ability triggers only once each turn."

Time Wipe

Return a creature you control to its owner's hand, then destroy all creatures.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Counterspell

Talisman of Progress

{T}: Add {C}.
{T}: Add {W} or {U}. Talisman of Progress deals 1 damage to you.

Vodalian Hexcatcher

Flash
Other Merfolk you control get +1/+1.
Sacrifice a Merfolk: Counter target noncreature spell unless its controller pays {1}.

Svyelun of Sea and Sky

Svyelun of Sea and Sky has indestructible as long as you control at least two other Merfolk.
Whenever Svyelun attacks, draw a card.
Other Merfolk you control have ward {1}. (Whenever another Merfolk you control becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)