msem-instigator

Search your library for a Forest card, put it onto the battlefield, then shuffle.

Target player sacrifices a nontoken creature and mills three cards.

Attacking creatures get +2/+0 and gain trample until end of turn.

Flying
When Intrepid enters, search your library for a land card, reveal it, put it into your hand, then shuffle.
Wanderlust — {0}: Intrepid becomes an artifact creature until end of turn. Activate only if you control four or more differently named lands.

At the beginning of combat on your turn, create a 1/1 blue and red Pirate creature token with haste. That token attacks this combat if able.
Whenever Intrepid Captain attacks, other attacking Pirates you control get +1/+0 until end of turn.

Improve {W} ({W}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Whenever one or more embattled creatures you control attack, create a 1/1 white Cleric creature token with lifelink. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

When Intrepid Shieldmate enters, target creature gets +1/+1 until end of turn.

Flash
When Intrepid Shooter enters, it deals 2 damage to target attacking creature.

Advance {4}{R} (Cast this for {4}{R} to advance it as it enters. {4}{R}: Advance this as a sorcery.)
Whenever Intruder Drone advances, exile the top card of your library. You may cast a spell exiled with Intruder Drone with mana value 3 or less without paying its mana cost.

({T}: Add {U}.)
Inundated Sanctuary enters tapped with two sanctum counters on it.
{T}, Remove a sanctum counter from Inundated Sanctuary: Add {W} or {B}.

Counter target spell unless its controller pays {1}.

Draw X cards.
Flashback—{U}{U}{U}, Sacrifice X permanents. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Inversion of Flesh deals 5 damage to each creature and each planeswalker, and 5 damage to each player with the highest life total or tied for highest life total among players.

Untap all creatures you control.
Draw a card.

Create two 1/1 green Elf creature tokens, then up to one target creature gets +X/+X until end of turn, where X is the number of creatures you control. (Targets are chosen before the tokens are created.)

At the beginning of your upkeep, rouse 1. Then if you control a creature with power 5 or greater, put a +1/+1 counter on each creature you control. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)

Put a +1/+1 counter on target creature. It gains indestructible until end of turn.

Inviolable Realms enters tapped unless you control two or more other lands.
{T}: Add {U}.
{T}, Pay 1 life: Add {W} or {B}.

Equipped creature has hexproof.
{2}: Exile equipped creature. Return it to the battlefield under its owner's control at the beginning of the next end step.
Equip {1}

Draw a card for each Avatar you control.

Hexproof
Invisible Stalker can't be blocked.

Gain control of target creature until end of turn. Put a +1/+1 counter on it and another target creature you control and untap them. Those creatures gains haste until end of turn.

Target opponent reveals cards from the top of their library until they reveal two instant and/or sorcery cards. Exile those cards, then that player shuffles the rest into their library. You may cast cards exiled this way until end of turn, and you may cast them without paying their mana costs.

Look at the top X cards of your library, where X is two plus the number of creatures you control. Exile up to two of them, then put the rest on the bottom in a random order. You may play the exiled cards until the end of your next turn.

Create two 2/2 blue Drake creature tokens with flying.
Metamorph {1}{U}{U} (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.)