msem-instigator

Flying, lifelink

Tap an untapped Desert you control: Hostile Atmosphere deals 1 damage to any target.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Lifelink

Target player creates two 1/1 white Spirit creature tokens with flying.
Fabled {3}{W}{W} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that player.)

Menace
Whenever an opponent activates an ability of a permanent, if it isn't a mana ability, Howling Shieldbreaker deals 2 damage to that permanent or player.

First mate—Your starting deck contains only cards with mana value 0, 1, or 3. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Menace
Once each turn, when one or more sources you control deal damage, you may put a +1/+1 counter on Hugo.

Menace
Whenever Hui Zhou, the Dark Visage perseveres, you may destroy another target legendary creature. (A creature perseveres when it survives damage.)

Humble Fieldhand gets +1/+0 and has vigilance as long as you control an Equipment.

Menace
Other Zombies you control get +1/+1.
Whenever a Zombie you control dies, each opponent loses 1 life.

Scry 3, then reveal the top card of your library. If it's a creature card, Hunter's Instinct deals damage to target creature equal to the revealed card's power.
Ferocious — If the revealed card is a creature card with power 4 or greater, put it into your hand.

Hurtling Swine attacks each combat if able.

Counter target spell. If that spell is countered this way, its owner puts it on the top or bottom of their library instead of into their graveyard.
Each player draws a card.

Enchant creature
When Hypnotic Halo enters, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
{2}{W}{W}, Sacrifice Hypnotic Halo: Exile enchanted creature.

Enchant artifact or creature
Enchanted permanent doesn't untap during its controller's untap step.

Icecap Tortoise enters with three ice counters on it.
Icecap Tortoise has defender as long as it has an ice counter on it.
{1}{U}: Remove an ice counter from Icecap Tortoise.

You may have Icefang Wurm assign its combat damage as though it weren't blocked.
{4}{G}{G}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)

{1}, {T}: Tap target artifact, creature, or land.

Flying
Whenever Idol of the Dead God deals combat damage to a player, search your library for any number of creature cards named Idol of the Dead God, reveal them, put them into your hand, then shuffle.

Flying, vigilance, lifelink
Idyllic Pegasus gets +1/+0 for each artifact and/or enchantment you control.

When Iekin's Portal enters, look at the top five cards of your library. Put one into your hand and the rest into your graveyard.
{1}{U}{U}: Transform Iekin's Portal. Activate only if your fealty to Islands is five or greater.

Indestructible
You have no maximum hand size.
Whenever an opponent draws a card, you draw a card.
If you would lose the game other than for having 0 or less life, you win the game instead. (Another player winning the game does not cause you to lose the game.)

Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Igneous Pulverizer desecrates a permanent, destroy target nonland permanent.

When Illustrious Lantern enters, put a +1/+1 counter on target creature you control.
{4}, {T}: Put a +1/+1 counter on target creature you control.

Distribute three +1/+1 counters among any number of creatures you control.
Metamorph {1}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

Immolated Grave enters tapped.
{T}: Add {R}.
{2/R}{2/R}: Immolated Grave becomes a 3/1 red Elemental creature with first strike until end of turn. It's still a land.