msem-instigator

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.

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.

Return target creature to its owner's hand. Create a 2/2 green Bear Actor creature token.

As Exodus of the Khalizors enters, choose Rehison or Danuri.
• Rehison — Whenever an Elf you control enters, you may move a counter from target creature onto another target creature.
• Danuri — Soldiers you control have trample.

Exile target creature. Search its controller's graveyard and library for any number of cards with the same name as that creature and exile them. Then that player shuffles.

Until end of turn, whenever you cast an instant or sorcery spell, you may discard a card. If you do, draw a card.

Creatures you control get +2/+0 until end of turn. Scouts you control gain trample until end of turn.

Other Elves you control get +1/+1.
Whenever another Scout you control deals combat damage to a player, you may reveal the top card of your library. If it's a land card, put it onto the battlefield tapped.

When Expedition Outfitter enters, create a 1/1 colorless Servo artifact creature token.
At the beginning of each end step, if an artifact was put into your graveyard from the battlefield this turn, Expedition Outfitter deals 1 damage to each opponent.

Put target nonland permanent on top of its owner's library.
Draw a card.

Foretell {U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)
Target creature gets -4/-0 until end of turn.
Draw a card.

Target player chooses a creature they control, then returns all other creatures they control to their owners' hands.

Cycling {3} ({3}, Discard this card: Draw a card.)

When Expensive Tutor enters, tap target land. It doesn't untap during its controller's next untap step.

When Experienced Team enters, choose one —
• Create a 4/2 white Bear creature token.
• Create a 2/4 red Snail creature token.
• Create a 2/2 white Bird creature token with flying.

Flash
You may activate Zero's loyalty abilities any time you could cast an instant on your turn and the turn they entered.
[+2]: Destroy up to one target permanent with mana value 4 or greater.
[–2]: You may cast a spell with mana value 5 or less from your hand without paying its mana cost.
[–3]: Look at the top six cards of your library. Put one of them into your hand and the rest on the bottom of your library in a random order.

Draw three cards. (Then exile this card. You may cast the creature later from exile.)

Mill five cards, then return up to one creature card, up to one land card, and up to one noncreature, nonland card from your graveyard to your hand. Exile Explore Forgotten Lands.

At the beginning of your upkeep, choose one. If you control seven or more differently named permanents, choose two instead.
• Draw a card.
• Explore the Multiverse deals 2 damage to target player.
• Create a 1/1 white Scout creature token.

Enchant opponent
At the beginning of enchanted player's upkeep, you create a 3/2 green Crocodile creature token with trample if enchanted player has 10 or less life. Otherwise, they lose 2 life.

Explosive Implant deals 4 damage to target creature and 2 damage to that creature's controller.

This spell costs {2} less to cast if you control an Azra or Demon.
Target creature you control gets +4/+4 and gains trample until end of turn.