msem-instigator

First strike
Tesqua Cohort enters with a +1/+1 counter on it if you control another creature with a +1/+1 counter on it.

Enchant creature
Enchanted creature has vigilance.
Whenever enchanted creature attacks or blocks, you gain 2 life.

Calfu, Greatest Toqui is all colors.
As long as there are five or more basic land types among lands you control, other creatures you control get +2/+1 and have vigilance.
When Calfu dies, you may search your library for a card named Heart of Carü Mapu, put it onto the battlefield, then shuffle.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
{X}{R}: Hearth Dweller gets +X/+0 until end of turn.

Dragon's Wrath deals 5 damage to target creature or planeswalker and 2 damage to that permanent's controller.

{1}, {T}: Exile target card from a graveyard. Scry 1.
{T}, Exile Soul Gate: Exile all graveyards.

As an additional cost to cast this spell, you may tap any number of untapped tokens you control. This spell costs {1} less to cast for each token tapped this way.
Whenever Organic Dreadnought enters or attacks, tap target permanent an opponent controls. That permanent doesn't untap during its controller's next untap step.

Civilized — Adorned Naga gets +2/+0 and has menace as long as you control an artifact, a creature, and an enchantment.

Counter target spell. Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Incendiary Flow deals 3 damage to any target. If a creature dealt damage this way would die this turn, exile it instead.

Fahrib's Tongue can't be blocked by creatures with two or more creature types.
Whenever Fahrib's Tongue deals combat damage to a player, that player loses 1 life for each creature that dealt damage to them this turn.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Whenever a creature you control attacks alone, untap all lands you control.

Return target creature card from your graveyard to your hand. If that card is a Human, you gain 3 life.
Flashback {3}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Draw three cards. If you control a Wizard, untap up to three lands.

Prowess
When Rosebud Runner enters, exile the top card of your library. During your next turn, you may play that card from exile.

Menace
Augmented — When Gravitational Ripper enters, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, target opponent sacrifices a creature. If they can't, they discard a card.

Return target creature to its owner's hand. Another target creature gets -6/-0 until end of turn.

When Artificial Wayfinder enters, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create four 1/1 colorless Construct Actor creature tokens.
II — Each player sacrifices a nontoken creature.
III — Each player loses 3 life.

[+1]: Discard a card. If you do, up to one target player gains 5 life.
[–3]: Discard a card. You draw X cards and you lose X life, where X is that card's mana value.
[–7]: Exile your hand, then put all cards from your graveyard into your hand and all cards exiled this way into your graveyard.

When The Clocktower Project enters, create a tapped colorless Powercell artifact token with “{T}: Add {C}.”
Tap seven untapped artifacts you control: Draw three cards.

Return target creature card with mana value 3 or less from your graveyard to the battlefield. If its mana value is less than 3, you gain life equal to the difference.

Advance {3}{R} (Cast this for {3}{R} to advance it as it enters. {3}{R}: Advance this as a sorcery.)
Whenever another artifact creature you control enters or a permanent you control advances, Skalorian Orbguard deals 1 damage to any target.

While searching your library, you may play basic land cards from your library.
You may play an additional land each turn.

Whenever a creature you control is dealt damage, put a +1/+1 counter on that creature.