Merfolk Sovereign

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

Hamlet Captain

Whenever Hamlet Captain attacks or blocks, other Humans you control get +1/+1 until end of turn.

Predatory Sliver

Invisible Stalker

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Invisible Stalker can't be blocked.

Amoeboid Changeling

Changeling (This card is every creature type.)
{T}: Target creature gains all creature types until end of turn.
{T}: Target creature loses all creature types until end of turn.

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}.)

Squirrel Sovereign

Corsair Captain

When Corsair Captain enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Other Pirates you control get +1/+1.

Elvish Archdruid

Other Elf creatures you control get +1/+1.
{T}: Add {G} for each Elf you control.

Muscle Sliver

Pheres-Band Warchief

Vigilance, trample
Other Centaur creatures you control get +1/+1 and have vigilance and trample.

Three Tree Mascot

Changeling (This card is every creature type.)
{1}: Add one mana of any color. Activate only once each turn.

Slippery Bogle

Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Spyglass Siren

Flying
When Spyglass Siren enters, create a Map token. (It's an artifact with "{1}, {T}, Sacrifice this artifact: Target creature you control explores. Activate only as a sorcery.")

Masked Vandal

Changeling (This card is every creature type.)
When Masked Vandal enters, you may exile a creature card from your graveyard. If you do, exile target artifact or enchantment an opponent controls.

Urza's Mine

{T}: Add {C}. If you control an Urza's Power-Plant and an Urza's Tower, add {C}{C} instead.

Supreme Phantom

Flying
Other Spirits you control get +1/+1.

Woodland Changeling

Changeling (This card is every creature type.)

Diffusion Sliver

Whenever a Sliver creature you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {2}.

Toadstool Admirer

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
{3}{G}: Put a +1/+1 counter on Toadstool Admirer.

Guardian Gladewalker

Changeling (This card is every creature type.)
When Guardian Gladewalker enters, put a +1/+1 counter on target creature.

Feline Sovereign

Other Cats you control get +1/+1 and have protection from Dogs.
Whenever one or more Cats you control deal combat damage to a player, destroy up to one target artifact or enchantment that player controls.

Scuttling Sliver

Sliver creatures you control have "{2}: Untap this creature."

Cloudpost

Cloudpost enters tapped.
{T}: Add {C} for each Locus on the battlefield.

Slither Blade

Merrow Reejerey

Other Merfolk creatures you control get +1/+1.
Whenever you cast a Merfolk spell, you may tap or untap target permanent.

Rishkar, Peema Renegade

When Rishkar, Peema Renegade enters, put a +1/+1 counter on each of up to two target creatures.
Each creature you control with a counter on it has "{T}: Add {G}."

Leaf-Crowned Visionary

Other Elves you control get +1/+1.
Whenever you cast an Elf spell, you may pay {G}. If you do, draw a card.

Gladecover Scout

Master of the Pearl Trident

Other Merfolk creatures you control get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

Mothdust Changeling

Changeling (This card is every creature type.)
Tap an untapped creature you control: Mothdust Changeling gains flying until end of turn.

Merfolk Mistbinder

Scion of Oona

Flash
Flying
Other Faerie creatures you control get +1/+1.
Other Faeries you control have shroud. (They can't be the targets of spells or abilities.)

Sporecrown Thallid

Each other creature you control that's a Fungus or Saproling gets +1/+1.

Shadow Sliver

All Sliver creatures have shadow. (They can block or be blocked by only creatures with shadow.)

Universal Automaton

Spore Frog

Sacrifice Spore Frog: Prevent all combat damage that would be dealt this turn.

Omo, Queen of Vesuva

Whenever Omo, Queen of Vesuva enters or attacks, put an everything counter on each of up to one target land and up to one target creature.
Each land with an everything counter on it is every land type in addition to its other types.
Each nonland creature with an everything counter on it is every creature type.

Urza's Power Plant

{T}: Add {C}. If you control an Urza's Mine and an Urza's Tower, add {C}{C} instead.

Gemhide Sliver

All Slivers have "{T}: Add one mana of any color."

Vodalian Hexcatcher

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

Whelming Wave

Return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.

Urza's Tower

{T}: Add {C}. If you control an Urza's Mine and an Urza's Power-Plant, add {C}{C}{C} instead.

Adaptive Automaton

As Adaptive Automaton enters, choose a creature type.
Adaptive Automaton is the chosen type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

Patrician Geist

Flying
Other Spirits you control get +1/+1.
Spells you cast from your graveyard cost {1} less to cast.

Lord of the Unreal

Illusion creatures you control get +1/+1 and have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Imperious Perfect

Other Elves you control get +1/+1.
{G}, {T}: Create a 1/1 green Elf Warrior creature token.

Priest of Titania

{T}: Add {G} for each Elf on the battlefield.

Howlpack Alpha

Each other creature you control that's a Werewolf or a Wolf gets +1/+1.
At the beginning of your end step, create a 2/2 green Wolf creature token.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform Howlpack Alpha.

Mayor of Avabruck

Other Human creatures you control get +1/+1.
At the beginning of each upkeep, if no spells were cast last turn, transform Mayor of Avabruck.

Mayor of Avabruck // Howlpack Alpha

Manaweft Sliver

Sliver creatures you control have "{T}: Add one mana of any color."

Elvish Clancaller

Other Elves you control get +1/+1.
{4}{G}{G}, {T}: Search your library for a card named Elvish Clancaller, put it onto the battlefield, then shuffle.