msem-instigator

{2}, {T}: Reveal the bottom card of your library. You gain life equal to its mana value. You may put it into your graveyard.

First strike
When Excavator of the Beyond enters, rediscover an artifact card. (Look at the top card of your library. You may reveal it and put it into your hand if it's an artifact card. Otherwise, put it back or into your graveyard.)

Scry 5.

{T}: Draw a card, then discard a card.
Whenever you cast an instant or sorcery spell, untap Exchange Scholar.

Exile target creature and all other creatures with the same name as that creature. Search all graveyards, hands, and libraries for any number of cards with the same name as that creature and exile them. Then players shuffle their libraries searched this way.

Harmony — Exciting Band deals 3 damage to any target.
When Exciting Band enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Counter target creature spell.
Draw a card.

Spells you cast from anywhere other than your hand can't be countered.
Whenever an opponent casts a spell with the same name as a card they own in exile or in their graveyard, you may draw a card.

Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Exemplar of Disdain desecrates a permanent, target creature you don't control gets -3/-3 until end of turn.

First strike, vigilance, lifelink

Destroy target creature with power equal to its toughness.

When Exergetic Chains enters, exile target nonland permanent you don't control and up to one target creature you control until Exergetic Chains leaves the battlefield.

Each player sacrifices a creature.

Target creature gets -X/-X until end of turn, where X is its base toughness.

Vigilance
{G}, {T}: Exile up to three target cards from graveyards. If two or more of those cards share a card type, create a 1/1 colorless Servo artifact creature token.

{1}, {T}, Exile a land card from your graveyard: Add two mana in any combination of colors.
{B}{G}, {T}, Discard a card: Nourish 2. (To nourish 2, either put two +1/+1 counters on this creature or create two 1/1 white Citizen creature tokens.)

Put target spell on top of its owner's library.
Each player conjures a card named Fatigue and puts it on top of their library. (It's a colorless sorcery that costs {2} with “Draw a card.”)

If a player would draw one or more cards, instead that player draws that many cards plus one and loses 1 life.

{1}: Put a -1/-1 counter on target creature you control. Untap that creature.

Gain control of target creature until end of turn. Untap that creature. Until end of turn, it gains haste and “Whenever this creature deals combat damage to a player, aetherize it.” (To aetherize, create a token that's a copy of it, then exile that token.)

Whenever you cast a spell, put a lore counter on Exhilarating Prescience.
At the beginning of your upkeep, exile the top X cards of your library, where X is the number of lore counters on Exhilarating Prescience. You may play those cards until your next turn.

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle. Create three 1/1 Scout creature tokens that are all colors.

Infiltrate (Whenever one or more attacking creatures you control aren't blocked, this creature gets +1/+1 until end of turn.)
When Exile's Vanguard enters, tap target creature. That creature doesn't untap during its controller's next untap step.

When Exiled Necromancer enters, return target permanent card with mana value 1 or less from your graveyard to the battlefield.

Infiltrate (Whenever one or more attacking creatures you control aren't blocked, this creature gets +1/+1 until end of turn.)
When Exiled Warband dies, draw a card.