msem-instigator

Whenever Implant Tinkerer or another artifact you control enters, choose one —
• Put a +1/+1 counter on that artifact.
• Implant Tinkerer deals 1 damage to any target and you gain 1 life.

Flash
Defender
When Imposing Barricade enters, target creature doesn't untap during its controller's untap step for as long as you control Imposing Barricade.

Harmony — Target creature gains indestructible until end of turn.
When Improvising Automaton enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Advance {1}{R}{R} (Cast this for {1}{R}{R} to advance it as it enters. {1}{R}{R}: Advance this as a sorcery.)
Whenever Impulse Module enters or advances, put a charge counter on it, then exile a card from the top of your library for each charge counter on it. Until your next turn, you may play one of those cards.

Equipped creature gets +3/+2 and must be blocked by a creature that doesn't share a color with it if able.
Equip {4}

Advance {3}{W}{W} (Cast this for {3}{W}{W} to advance it as it enters. {3}{W}{W}: Advance this as a sorcery.)
Whenever Inconspicuous Loxodon advances, search your library for an Equipment card, put it onto the battlefield, then shuffle.
As long as Inconspicuous Loxodon is enchanted or equipped, he's a 5/5 legendary Elephant Rogue named Agent E.

Hexproof
Whenever another creature you control becomes the target of a spell an opponent controls, you may submerge that creature. (To submerge a card, exile it, then put it on the battlefield face down under its owner's control as a 2/2 creature.)
{1}{U}{U}: Turn target face-down creature you control face up.

{3}, {T}: Put Ing'Wei's Crystal Top on top of your library. Scry 3, then draw a card.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
[+1]: Scry 1. If you're in a renaissance, draw a card.
[–2]: Return target nonland permanent to its owner's hand if its mana value is 3 or less or if you're in a renaissance.
[–6]: Create two 8/8 blue Kraken creature tokens. If you're in a renaissance, take an extra turn after this one.

[+1]: Look at the top two cards of your library. Put one of them into your hand and the other into your graveyard.
[–2]: Return target card from your graveyard to the battlefield face down.
[–6]: Turn any number of face-up nonland permanents of your choice face down.

Whenever Inishtu, Desert Healer enters or attacks, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
At the beginning of your upkeep, if seven or more cards are in your graveyard, you may transform Inishtu.

Indestructible
{2}{B}, Exile two cards from your graveyard: Each opponent loses 2 life and you gain 2 life.

{T}: Add {U} or {R}. Spend this mana only to cast an instant, sorcery, or Wizard spell.
Whenever you cast your second spell each turn, untap Innova.

{T}, Sacrifice a land: Destroy target land.

Inquirer, Roaming Rover attacks each combat if able.
Whenever Inquirer deals damage to an opponent, draw a card.

[+1]: Each opponent puts a -1/-1 counter on a creature they control.
[–1]: Exile target card in a graveyard. You gain life equal to its mana value.
[–6]: Choose a number. You draw that many cards and you lose that much life.

{3}{B}, {T}: Choose a card name. Target player reveals cards from the top of their library until they reveal a card with the chosen name. If they do, put the revealed cards into their graveyard. Otherwise, they shuffle their library.

Whenever you cast your first instant or sorcery spell each turn, untap equipped creature.
Equip {1}

{4}, {T}: Put a -1/-1 counter on target creature.
{4}, {T}: Remove a -1/-1 counter from target creature.

Whenever a creature you control dies, Insidious Terror gets +1/+0 and gains menace until end of turn.

{2}, {T}: Put a +1/+1 counter on target creature you control.
{2}, {T}, Sacrifice Inspiring Effigy: Put a +1/+1 counter on each creature you control.

Equipped creature gets +1/+2.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Flying
{1}{W}: Exile target artifact you control. Return that card to the battlefield under your control at the beginning of the next end step.

Flying, ward {2}
Intisuyu's Masterpiece gets +X/+X, where X is the number of artifacts and/or enchantments you control.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
Put a +1/+1 counter on target creature you control.
Double the number of counters on target creature you control.