msem-instigator

If a creature entering the battlefield under your control causes a triggered ability of that creature to trigger, you may exile it. If you do, that ability triggers an additional time.

Vision (Whenever this or another creature you control enters, reveal the top card of your library. Then you may put that card into your graveyard.)
Whenever Aether Recoverer envisions a creature card, return target noncreature card from your graveyard to your hand.

When Aether Road Caravan enters, gain control of target nonland permanent with mana value 3 or less for as long as you control Aether Road Caravan.

When Aether Sculptor enters, create a tapped colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”

Prowess
At the beginning of each end step, if you cast a multicolor spell or two spells with different colors this turn, each opponent sacrifices a permanent.

Whenever you make first contact, you may draw a card. If you do, put a card from your hand on the bottom of your library. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

If a creature dealt damage by equipped creature this turn would die, exile that card and draw a card instead.
Equip {1}

You control equipped creature.
Equipped creature has hexproof and can't attack or block.
{3}: Attach Aetherite Shackles to target creature. Activate only as a sorcery.

Flash
Enchant permanent or spell
Whenever enchanted permanent or spell deals damage to a creature, return that creature to its owner's hand (if it's still on the battlefield).

When Aetherite Vein enters, scry 1.
{U}, Sacrifice Aetherite Vein: Return target creature to its owner's hand.

Defender, reach
Aetherlock Effigy can block an additional creature each combat.
When Aetherlock Effigy dies, create two 1/1 black Bird creature tokens with flying.

Equipped creature gets +1/+0 and has first strike.
{1}{R}: Equipped creature gets +1/+0 until end of turn.
Equip {2}

When Aethermancer's Companion enters, aetherize up to two other non-Cat permanents you control. (Create tokens that are copies of each of them, then exile them.)
Recite {5}{W}{U} (You may cast this spell from your graveyard for its recite cost. If you do, exile it when it enters or if it would leave the battlefield.)

Flash
When Aethermancer's Familiar enters, at the beginning of the next end step, you may aetherize target creature you control. (To aetherize, create a token that's a copy of it, then exile that token.)

Equipped creature gets +2/+1.
Equip multicolored creature {1}
Equip {2}

At the beginning of your end step, you lose 3 life unless you sacrifice a creature.

Flash
If you would upgrade a creature you control, you may put a +1/+1 counter on it instead.
{3}{U}: Put a +1/+1 counter on Affluent Cetanthrope and draw a card.

When Affluent Knight enters, recruit, then recruit again. (To recruit, create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)

When Aftermath of the Surge enters, create two Treasure tokens.
{1}{U}, Sacrifice two artifacts: Draw two cards.
{3}{U}, Sacrifice four artifacts: Create an 8/8 blue Kraken creature token. It can't block this turn.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Scry 2.
II — Draw two cards.
III — Spells you cast this turn cost {2} less to cast.

When Ageless Ascetic enters, return up to one target instant or sorcery card from your graveyard to your hand.

Flying
When Ageless Lorekeeper enters, you may discard your hand. When you do, draw three cards.

Whenever a land you control enters, untap Ageless Wanderer.
{1}, {T}: Add one mana of any color.

When Ageless Weaver enters, create a green Aura enchantment token named Years of Experience attached to target creature. The token has enchant creature and “Enchanted creature gets +2/+2.”
Whenever an enchanted creature you control dies, create a 3/3 green Elemental creature token.

Improve {1} ({1}: 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.)
Once each turn, when one or more counters are put on a permanent you control, create a 1/1 colorless Human creature token.
Whenever you attack with three or more creatures, destroy up to one target artifact or enchantment.