Resolute Watchdog

Defender
{1}, Sacrifice Resolute Watchdog: Target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

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.

Prowling Serpopard

This spell can't be countered.
Creature spells you control can't be countered.

King of the Pride

Irregular Cohort

Changeling (This card is every creature type.)
When Irregular Cohort enters, create a 2/2 colorless Shapeshifter creature token with changeling.

Regal Caracal

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

Taurean Mauler

Changeling (This card is every creature type.)
Whenever an opponent casts a spell, you may put a +1/+1 counter on Taurean Mauler.

Mirror Entity

Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.

Temur Sabertooth

{1}{G}: You may return another creature you control to its owner's hand. If you do, Temur Sabertooth gains indestructible until end of turn.

Universal Automaton

Changeling (This card is every creature type.)

Pack Leader

Other Dogs you control get +1/+1.
Whenever Pack Leader attacks, prevent all combat damage that would be dealt this turn to Dogs you control.

Wild Nacatl

Wild Nacatl gets +1/+1 as long as you control a Mountain.
Wild Nacatl gets +1/+1 as long as you control a Plains.

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.)

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.

Arcane Signet

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

Beastmaster Ascension

Whenever a creature you control attacks, you may put a quest counter on Beastmaster Ascension.
As long as Beastmaster Ascension has seven or more quest counters on it, creatures you control get +5/+5.

Whitemane Lion

Flash
When Whitemane Lion enters, return a creature you control to its owner's hand.

Leonin Warleader

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

Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

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.

Crib Swap

Changeling (This card is every creature type.)
Exile target creature. Its controller creates a 1/1 colorless Shapeshifter creature token with changeling.

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.

Selfless Savior

Sacrifice Selfless Savior: Another target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Ajani's Pridemate

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

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.)

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.)

Bolt Hound

Haste (This creature can attack and {T} as soon as it comes under your control.)
Whenever Bolt Hound attacks, other creatures you control get +1/+0 until end of turn.

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.

Akoum Hellhound

Landfall — Whenever a land you control enters, Akoum Hellhound gets +2/+2 until end of turn.

Hound of Griselbrand

Double strike
Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Animal Sanctuary

{T}: Add {C}.
{2}, {T}: Put a +1/+1 counter on target Bird, Cat, Dog, Goat, Ox, or Snake.

Keeper of Fables

Whenever one or more non-Human creatures you control deal combat damage to a player, draw a card.

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Boros Mastiff

Battalion — Whenever Boros Mastiff and at least two other creatures attack, Boros Mastiff gains lifelink until end of turn. (Damage dealt by a creature with lifelink also causes its controller to gain that much life.)

Rin and Seri, Inseparable

Whenever you cast a Dog spell, create a 1/1 green Cat creature token.
Whenever you cast a Cat spell, create a 1/1 white Dog creature token.
{R}{G}{W}, {T}: Rin and Seri, Inseparable deals damage to any target equal to the number of Dogs you control. You gain life equal to the number of Cats you control.

White Sun's Zenith

Create X 2/2 white Cat creature tokens. Shuffle White Sun's Zenith into its owner's library.