Solidarity
Whenever Inspired Denizen attacks, create a 1/1 green Citizen creature token that's tapped and attacking.

Enchant creature
Whenever enchanted creature deals or is dealt damage, exile it.

Trample
Whenever Insurgency Mentor attacks, teach target attacking creature with lesser power trample.

Enchant land
When International Development enters, make a pledge.
Enchanted land has “{T}: Add two mana of different colors.”

Interrogation Chamber enters tapped.
{T}: Add {U} or {B}.
{4}: Make a pledge. Activate only as a sorcery.

When Invader of Privacy enters, surveil 1, then draw a card.

Enchant creature
Whenever enchanted creature attacks, create a Treasure token.
If enchanted creature would die, instead sacrifice Invest and return that creature to its owner's hand.

Favored
Legendary permanents you control have haste and “Ward—Pay 3 life.”

Deathtouch
Cybersoul {4}{B}

When Iris Cultist enters, you lose 1 life.
Cybersoul {4}{B}

Deathtouch
When this creature transforms into Iris Flayer, target player draws a card and loses 1 life.

Indestructible
As long as your devotion to red and white is less than seven, Iroas isn't a creature.
Whenever you attack, you gain 1 life for each attacking creature. If you gained 5 or more life this way, draw a card.

Trample
Whenever Iron Steambreaker attacks, put a +1/+1 counter on it.

Vigilance, trample
{2}{R}{W}: Any number of target creatures you control have base power and toughness 6/6 until end of turn.

When Ironback Tyke enters, you may search your library for a basic Mountain or Plains card, reveal it, put it into your hand, then shuffle.
{2}{R}{W}: Any number of target creatures you control have base power and toughness 3/3 until end of turn. If you control seven or more permanents with activated abilities, transform Ironback Tyke. Activate only as a sorcery.

Whenever you cast an instant or sorcery spell, Ironcliff Blaster gets +1/+1 and gains first strike until end of turn.

Flying
Whenever Irrlicht deals combat damage to a player, they reveal their hand and you choose a nonland card from it. Exile that card until your next turn.

Flying
If a Dragon you control would deal damage to an opponent, it deals that much damage plus 1 instead.
{2}{U}{R}: Transform Iviana's Spellmaw.

Flying, trample
If a source you control would deal damage to an opponent or a permanent an opponent controls, you may have it deal twice that much damage instead if it's a Dragon or Iviana planeswalker. Otherwise, it deals that much damage plus 2 instead.

Dragons you control have ward {2} and haste.
[+1]: Iviana deals X damage to up to one target creature or planeswalker, where X is 2 plus twice the number of Dragons you control.
[–2]: You may reveal a Dragon card you own from outside the game and put it into your hand. Create two Treasure tokens.

Flying
Exile an instant or sorcery spell you control with mana value X: Choose one —
• You gain three times X life.
• Draw X cards, then discard a card.
• Put X +1/+1 counters on JJ Mack.

Whenever one or more permanent cards are put into graveyards, each opponent loses 1 life and you gain 1 life.
[+2]: Mill two cards.
[+1]: Sacrifice a land or discard a land card. If you do, you may play target creature or land card in your graveyard this turn.
[–3]: Each player sacrifices a creature. Return a creature card from your graveyard to your hand.

Haste
Whenever Jens Slopeskidder or a land you control enters, put a +1/+1 counter on target creature you control.
Wander—{1}{G}, Return a land you control to its owner's hand.

Flying
Discard a card: Put a +1/+1 counter on Jetstream Cruiser. Activate only once each turn.