Rhythm of the Wild

Creature spells you control can't be countered.
Nontoken creatures you control have riot. (They enter with your choice of a +1/+1 counter or haste.)

Simic Ascendancy

{1}{G}{U}: Put a +1/+1 counter on target creature you control.
Whenever one or more +1/+1 counters are put on a creature you control, put that many growth counters on this enchantment.
At the beginning of your upkeep, if this enchantment has twenty or more growth counters on it, you win the game.

Vampire

Sorin, Lord of Innistrad

Sorin, Lord of Innistrad Emblem

+1: Create a 1/1 black Vampire creature token with lifelink.
−2: You get an emblem with "Creatures you control get +1/+0."
−6: Destroy up to three target creatures and/or other planeswalkers. Return each card put into a graveyard this way to the battlefield under your control.

Hakbal of the Surging Soul

At the beginning of combat on your turn, each Merfolk creature you control explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on the exploring creature, then put the card back or put it into your graveyard.)
Whenever Hakbal attacks, you may put a land card from your hand onto the battlefield. If you don't, draw a card.

Tatyova, Benthic Druid

Landfall — Whenever a land you control enters, you gain 1 life and draw a card.

Tishana, Voice of Thunder

Tishana's power and toughness are each equal to the number of cards in your hand.
You have no maximum hand size.
When Tishana enters, draw a card for each creature you control.

Utter End

Vona, Butcher of Magan

Vigilance, lifelink
{T}, Pay 7 life: Destroy target nonland permanent. Activate only during your turn.

Vorel of the Hull Clade

{G}{U}, {T}: Double the number of each kind of counter on target artifact, creature, or land.

Xenagos, God of Revels

Indestructible
As long as your devotion to red and green is less than seven, Xenagos isn't a creature.
At the beginning of combat on your turn, another target creature you control gains haste and gets +X/+X until end of turn, where X is that creature's power.

Zacama, Primal Calamity

Vigilance, reach, trample
When Zacama enters, if you cast it, untap all lands you control.
{2}{R}: Zacama deals 3 damage to target creature.
{2}{G}: Destroy target artifact or enchantment.
{2}{W}: You gain 3 life.

Zara, Renegade Recruiter

Flying
Whenever Zara attacks, look at defending player's hand. You may put a creature card from it onto the battlefield under your control tapped and attacking that player or a planeswalker they control. Return that creature to its owner's hand at the beginning of the next end step.

Zegana, Utopian Speaker

When Zegana enters, if you control another creature with a +1/+1 counter on it, draw a card.
{4}{G}{U}: Adapt 4. (If this creature has no +1/+1 counters on it, put four +1/+1 counters on it.)
Each creature you control with a +1/+1 counter on it has trample.

Arcane Signet

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

Pantlaza, Sun-Favored

Whenever Pantlaza or another Dinosaur you control enters, you may discover X, where X is that creature's toughness. Do this only once each turn. (Exile cards from the top of your library until you exile a nonland card with that mana value or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

The Lost Caverns of Ixalan Commander