Prowling Serpopard

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

Ajani's Pridemate

Whenever you gain life, put a +1/+1 counter on this creature.

Prowling Felidar

Vigilance
Landfall — Whenever a land you control enters, put a +1/+1 counter on Prowling Felidar.

King of the Pride

Kutzil, Malamet Exemplar

Your opponents can't cast spells during your turn.
Whenever one or more creatures you control each with power greater than its base power deals combat damage to a player, draw a card.

Territorial Scythecat

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Landfall — Whenever a land you control enters, put a +1/+1 counter on Territorial Scythecat.

Graceful Cat

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

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.)

Phantom Tiger

Phantom Tiger enters with two +1/+1 counters on it.
If damage would be dealt to Phantom Tiger, prevent that damage. Remove a +1/+1 counter from Phantom Tiger.

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.

Sovereign Okinec Ahau

Ward {2}
Whenever Sovereign Okinec Ahau attacks, for each creature you control with power greater than that creature's base power, put a number of +1/+1 counters on that creature equal to the difference.

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.

Raksha Golden Cub

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

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.

Loam Lion

Loam Lion gets +1/+2 as long as you control a Forest.

Leonin Vanguard

At the beginning of combat on your turn, if you control three or more creatures, this creature gets +1/+1 until end of turn and you gain 1 life.

Lion Sash

{W}: Exile target card from a graveyard. If it was a permanent card, put a +1/+1 counter on Lion Sash.
Equipped creature gets +1/+1 for each +1/+1 counter on Lion Sash.
Reconfigure {2} ({2}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Phantom Nishoba

Trample
Phantom Nishoba enters with seven +1/+1 counters on it.
Whenever Phantom Nishoba deals damage, you gain that much life.
If damage would be dealt to Phantom Nishoba, prevent that damage. Remove a +1/+1 counter from Phantom Nishoba.

Unnatural Growth

At the beginning of each combat, double the power and toughness of each creature you control until end of turn.

Scrounging Bandar

Scrounging Bandar enters with two +1/+1 counters on it.
At the beginning of your upkeep, you may move any number of +1/+1 counters from Scrounging Bandar onto another target creature.

Pridemalkin

When Pridemalkin enters, put a +1/+1 counter on target creature you control.
Each creature you control with a +1/+1 counter on it has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Malamet War Scribe

When Malamet War Scribe enters, creatures you control get +2/+1 until end of turn.

Scythe Leopard

Landfall — Whenever a land you control enters, Scythe Leopard gets +1/+1 until end of turn.

Regal Caracal

Other Cats you control get +1/+1 and have lifelink. (Damage dealt by those creatures also causes you to gain that much life.)
When this creature enters, create two 1/1 white Cat creature tokens with lifelink.