The Circle of Loyalty

This spell costs {1} less to cast for each Knight you control.
Creatures you control get +1/+1.
Whenever you cast a legendary spell, create a 2/2 white Knight creature token with vigilance.
{3}{W}, {T}: Create a 2/2 white Knight creature token with vigilance.

Initiate's Companion

Whenever Initiate's Companion deals combat damage to a player, untap target creature or land.

Jedit Ojanen of Efrava

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)
Whenever Jedit Ojanen of Efrava attacks or blocks, create a 2/2 green Cat Warrior creature token with forestwalk.

Band Together

Up to two target creatures you control each deal damage equal to their power to another target creature.

Fleetfoot Panther

Flash
When Fleetfoot Panther enters the battlefield, return a green or white creature you control to its owner's hand.

Charge of the Forever-Beast

As an additional cost to cast this spell, reveal a creature card from your hand.
Charge of the Forever-Beast deals damage to target creature or planeswalker equal to the revealed card's power.

Arahbo, Roar of the World

Eminence — At the beginning of combat on your turn, if Arahbo, Roar of the World is in the command zone or on the battlefield, another target Cat you control gets +3/+3 until end of turn.
Whenever another Cat you control attacks, you may pay {1}{G}{W}. If you do, it gains trample and gets +X/+X until end of turn, where X is its power.

Crystalline Giant

At the beginning of combat on your turn, choose a kind of counter at random that Crystalline Giant doesn't have on it from among flying, first strike, deathtouch, hexproof, lifelink, menace, reach, trample, vigilance, and +1/+1. Put a counter of that kind on Crystalline Giant.

Balan, Wandering Knight

First strike
Balan, Wandering Knight has double strike as long as two or more Equipment are attached to it.
{1}{W}: Attach all Equipment you control to Balan.

Adorned Pouncer

Double strike
Eternalize {3}{W}{W} ({3}{W}{W}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a 4/4 black Zombie Cat with no mana cost. Eternalize only as a sorcery.)

Generous Stray

When Generous Stray enters the battlefield, draw a card.

Protection of the Hekma

If a source an opponent controls would deal damage to you, prevent 1 of that damage.

Bronzehide Lion

{G}{W}: Bronzehide Lion gains indestructible until end of turn.
When Bronzehide Lion dies, return it to the battlefield. It's an Aura enchantment with enchant creature you control and "{G}{W}: Enchanted creature gains indestructible until end of turn," and it loses all other abilities.

Patagia Tiger

Flying
When Patagia Tiger enters the battlefield, target Human you control gets +2/+2 until end of turn.

Sacred Cat

Lifelink
Embalm {W} ({W}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a white Zombie Cat with no mana cost. Embalm only as a sorcery.)

Hungry Lynx

Cats you control have protection from Rats. (They can't be blocked, targeted, or dealt damage by Rats.)
At the beginning of your end step, target opponent creates a 1/1 black Rat creature token with deathtouch.
Whenever a Rat dies, put a +1/+1 counter on each Cat you control.

Cavern Whisperer

Mutate {3}{B} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Menace (This creature can't be blocked except by two or more creatures.)
Whenever this creature mutates, each opponent discards a card.

Felidar Sovereign

Vigilance, lifelink
At the beginning of your upkeep, if you have 40 or more life, you win the game.

Frondland Felidar

Vigilance
Creatures you control with vigilance have "{1}, {T}: Tap target creature."

Plains

Kemba, Kha Regent

At the beginning of your upkeep, create a 2/2 white Cat creature token for each Equipment attached to Kemba, Kha Regent.

Reverse Damage

The next time a source of your choice would deal damage to you this turn, prevent that damage. You gain life equal to the damage prevented this way.

Cubwarden

Mutate {2}{W}{W} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Lifelink
Whenever this creature mutates, create two 1/1 white Cat creature tokens with lifelink.

Felidar Guardian

When Felidar Guardian enters the battlefield, you may exile another target permanent you control, then return that card to the battlefield under its owner's control.

Mace of the Valiant

Equipped creature gets +1/+1 for each charge counter on Mace of the Valiant and has vigilance.
Whenever a creature enters the battlefield under your control, put a charge counter on Mace of the Valiant.
Equip {3}

Dismal Backwater

Dismal Backwater enters the battlefield tapped.
When Dismal Backwater enters the battlefield, you gain 1 life.
{T}: Add {U} or {B}.

Cauldron Familiar

When Cauldron Familiar enters the battlefield, each opponent loses 1 life and you gain 1 life.
Sacrifice a Food: Return Cauldron Familiar from your graveyard to the battlefield.

Pride Sovereign

Pride Sovereign gets +1/+1 for each other Cat you control.
{W}, {T}, Exert Pride Sovereign: Create two 1/1 white Cat creature tokens with lifelink. (An exerted creature won't untap during your next untap step.)

Healer of the Pride

Whenever another creature enters the battlefield under your control, you gain 2 life.

Ajani's Chosen

Whenever an enchantment enters the battlefield under your control, create a 2/2 white Cat creature token. If that enchantment is an Aura, you may attach it to the token.

King of the Pride

Ajani's Sunstriker

Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Garrison Cat

When Garrison Cat dies, create a 1/1 white Human Soldier creature token.

Forest

Necropanther

Mutate {2}{W/B}{W/B} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Whenever this creature mutates, return target creature card with mana value 3 or less from your graveyard to the battlefield.

Blitz Leech

Flash
When Blitz Leech enters the battlefield, target creature an opponent controls gets -2/-2 until end of turn. Remove all counters from that creature.

The Great Henge

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
{T}: Add {G}{G}. You gain 2 life.
Whenever a nontoken creature enters the battlefield under your control, put a +1/+1 counter on it and draw a card.

Grizzled Leotau

Ferocious Zheng

Blood Curdle

Destroy target creature. Put a menace counter on a creature you control. (It can't be blocked except by two or more creatures.)

Maned Serval

Leonin Warleader

Whenever Leonin Warleader attacks, create two 1/1 white Cat creature tokens with lifelink that are tapped and attacking.

Bristling Boar

Bristling Boar can't be blocked by more than one creature.

Ajani's Pridemate

Whenever you gain life, put a +1/+1 counter on Ajani's Pridemate.

Fleecemane Lion

{3}{G}{W}: Monstrosity 1. (If this creature isn't monstrous, put a +1/+1 counter on it and it becomes monstrous.)
As long as Fleecemane Lion is monstrous, it has hexproof and indestructible.

Carrion Call

Create two 1/1 green Phyrexian Insect creature tokens with infect. (They deal damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Dazzling Reflection

You gain life equal to target creature's power. The next time that creature would deal damage this turn, prevent that damage.

Insatiable Hemophage

Mutate {2}{B} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Deathtouch
Whenever this creature mutates, each opponent loses X life and you gain X life, where X is the number of times this creature has mutated.

Gemrazer

Mutate {1}{G}{G} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Reach, trample
Whenever this creature mutates, destroy target artifact or enchantment an opponent controls.

Blade Banish

Exile target creature with power 4 or greater.

Boneyard Lurker

Mutate {2}{B/G}{B/G} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Whenever this creature mutates, return target permanent card from your graveyard to your hand.

Awe Strike

The next time target creature would deal damage this turn, prevent that damage. You gain life equal to the damage prevented this way.

Graceful Cat

Whenever Graceful Cat attacks, it gets +1/+1 until end of turn.

Brimaz, King of Oreskos

Vigilance
Whenever Brimaz, King of Oreskos attacks, create a 1/1 white Cat Soldier creature token with vigilance that's attacking.
Whenever Brimaz blocks a creature, create a 1/1 white Cat Soldier creature token with vigilance that's blocking that creature.

Grimdancer

Grimdancer enters the battlefield with your choice of two different counters on it from among menace, deathtouch, and lifelink.

Guardian Lions

Vigilance (Attacking doesn't cause this creature to tap.)

Lurrus of the Dream-Den

Companion — Each permanent card in your starting deck has mana value 2 or less. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
Lifelink
Once during each of your turns, you may cast a permanent spell with mana value 2 or less from your graveyard.

Qasali Slingers

Reach
Whenever Qasali Slingers or another Cat enters the battlefield under your control, you may destroy target artifact or enchantment.

Swamp

Raksha Golden Cub

Vigilance
As long as Raksha Golden Cub is equipped, Cat creatures you control get +2/+2 and have double strike.

Regal Caracal

Other Cats you control get +1/+1 and have lifelink.
When Regal Caracal enters the battlefield, create two 1/1 white Cat creature tokens with lifelink.

Hero of the Pride

Whenever you cast a spell that targets Hero of the Pride, creatures you control get +1/+0 until end of turn.

Huntmaster Liger

Mutate {2}{W} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Whenever this creature mutates, other creatures you control get +X/+X until end of turn, where X is the number of times this creature has mutated.

Colossification

Enchant creature
When Colossification enters the battlefield, tap enchanted creature.
Enchanted creature gets +20/+20.

Kaheera, the Orphanguard

Companion — Each creature card in your starting deck is a Cat, Elemental, Nightmare, Dinosaur, or Beast card. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
Vigilance
Each other creature you control that's a Cat, Elemental, Nightmare, Dinosaur, or Beast gets +1/+1 and has vigilance.

Felidar Cub

Sacrifice Felidar Cub: Destroy target enchantment.

Jareth, Leonine Titan

Whenever Jareth, Leonine Titan blocks, it gets +7/+7 until end of turn.
{W}: Jareth gains protection from the color of your choice until end of turn.

Glowstone Recluse

Mutate {3}{G} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Reach
Whenever this creature mutates, put two +1/+1 counters on it.

Aegis of Honor

{1}: The next time an instant or sorcery spell would deal damage to you this turn, that spell deals that damage to its controller instead.

Nethroi, Apex of Death

Mutate {4}{G/W}{B}{B} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Deathtouch, lifelink
Whenever this creature mutates, return any number of target creature cards with total power 10 or less from your graveyard to the battlefield.

Alms Collector

Flash
If an opponent would draw two or more cards, instead you and that player each draw a card.