Shared Animosity

Whenever a creature you control attacks, it gets +1/+0 until end of turn for each other attacking creature that shares a creature type with it.

Ajani's Pridemate

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

Aura Shards

Whenever a creature you control enters, you may destroy target artifact or enchantment.

Have

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Canyon Wildcat

Mountainwalk (This creature can't be blocked as long as defending player controls a Mountain.)

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.

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Second Harvest

For each token you control, create a token that's a copy of that permanent.

Alms Collector

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

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.

Anointed Procession

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Cat Warriors

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)

Jetmir, Nexus of Revels

Creatures you control get +1/+0 and have vigilance as long as you control three or more creatures.
Creatures you control also get +1/+0 and have trample as long as you control six or more creatures.
Creatures you control also get +1/+0 and have double strike as long as you control nine or more creatures.

Arcbound Mouser

Lifelink
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)