Merfolk Sovereign

Other Merfolk creatures you control get +1/+1.
{T}: Target Merfolk creature can't be blocked this turn.

Shaper Apprentice

Shaper Apprentice has flying as long as you control another Merfolk.

Forest

Soul of the Harvest

Trample
Whenever another nontoken creature you control enters, you may draw a card.

Prey Upon

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Kumena's Speaker

Kumena's Speaker gets +1/+1 as long as you control another Merfolk or an Island.

Tempest Caller

When Tempest Caller enters, tap all creatures target opponent controls.

Vow of Flight

Enchant creature
Enchanted creature gets +2/+2, has flying, and can't attack you or planeswalkers you control.

Waker of the Wilds

{X}{G}{G}: Put X +1/+1 counters on target land you control. That land becomes a 0/0 Elemental creature with haste. It's still a land.

Aether Gale

Return six target nonland permanents to their owners' hands.

Rancor

Enchant creature
Enchanted creature gets +2/+0 and has trample.
When Rancor is put into a graveyard from the battlefield, return Rancor to its owner's hand.

Time Warp

Target player takes an extra turn after this one.

Giant Growth

Target creature gets +3/+3 until end of turn.

Jungle Barrier

Defender (This creature can't attack.)
When Jungle Barrier enters, draw a card.

Deeproot Warrior

Whenever Deeproot Warrior becomes blocked, it gets +1/+1 until end of turn.

Concentrate

River Sneak

River Sneak can't be blocked.
Whenever another Merfolk you control enters, River Sneak gets +1/+1 until end of turn.

Watertrap Weaver

When Watertrap Weaver enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Prismatic Lens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Vineshaper Mystic

When Vineshaper Mystic enters, put a +1/+1 counter on each of up to two target Merfolk you control.

Threads of Disloyalty

Enchant creature with mana value 2 or less
You control enchanted creature.

Air Elemental

Unsummon

Return target creature to its owner's hand.

Unknown Shores

Island

Shapers of Nature

{3}{G}: Put a +1/+1 counter on target creature.
{2}{U}, Remove a +1/+1 counter from a creature you control: Draw a card.