msem-instigator

When Fae-Blessed Attendant enters, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Whenever you sacrifice a Clue, untap target permanent.

Pressure {B}{G} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
Search your library and/or graveyard for a creature card with mana value 3 or less and put it onto the battlefield. If you searched your library this way, shuffle.

When Master of the Glen enters, create a 2/2 green Wolf Elemental creature token.
Elementals you control have trample.

When Phyrexian Arcforger enters, create a 1/1 colorless Phyrexian artifact creature token for each artifact you control.

When Dutiful Camel enters, put a +1/+1 counter on target creature you control.

Battalion — Whenever Fellor Raider and at least two other creatures attack, Fellor Raider deals 2 damage to defending player.

Create a 1/1 red and green Elemental creature token. Creatures you control get +1/+1 and gain haste until end of turn.
Orchestrate {R}{G} (You may exile this card from your hand anytime you could cast a sorcery for its orchestrate cost. When you next resolve a spell, you may cast this from exile without paying its mana cost.)

Ferocious — Once each turn, when a creature you control with power 4 or greater enters, you may untap all lands you control.

Improve {W} ({W}: 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.)
Whenever one or more embattled creatures you control attack, create a 1/1 white Cleric creature token with lifelink. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Deception {U} ({U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever a Pirate or Rogue you control deals combat damage to a player, rediscover a Pirate or Rogue card. (Look at the top card of your library. You may reveal it and put it into your hand if it's a Pirate or Rogue. Otherwise, put it back or into your graveyard.)

Flying
Whenever Aether Crosser attacks, you may aetherize another target tapped creature you control. (To aetherize, create a token that's a copy of it, then exile that token.)
Crew 1

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — War's Sorrow deals 1 damage to any target.
III — Each player sacrifices another permanent. Put War's Sorrow on top of its owner's library unless a player has it deal 3 damage to them.

Regenerate target creature. (The next time that permanent would be destroyed this turn, it isn't. Instead tap it.)

Deathwind Survivor's power and toughness are each equal to the number of enchantments you control.
Whenever an enchantment you control enters, put a +1/+1 counter on target creature.

Flying
When Ascended Explorer enters, return target creature card with mana value 2 or less from your graveyard to the battlefield.

Enchant creature you control
Whenever enchanted creature attacks, mill three cards.
When enchanted creature leaves the battlefield, create an X/X green Spirit creature token, where X is equal to the number of card types among cards in your graveyard.

Equipped creature gets +1/+0 and has “Whenever this creature deals combat damage to a player, draw a card.”
Equip {3}

First strike
Noncreature spells cost {1} more to cast as long as their controller is horrific. (A player is horrific as long as they've sacrificed a permanent or discarded a card this turn.)

Enchant creature or artifact
When Meticulous Process enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Enchanted permanent doesn't untap during its controller's untap step.

Target opponent reveals their hand. You choose a creature or planeswalker card from it. That player discards that card.

Choose one—
• Counter target spell.
• Exile two target permanents you control, then return them to the battlefield under your control.

Choose one —
• Create two 1/1 white Soldier creature tokens. They gain haste until end of turn.
• Destroy target nonbasic land.

Each planeswalker you control enters with an additional loyalty counter on it.
{T}: Add {C}.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Create a token that's a copy of target Construct you control.
III — Constructs you control get +2/+0 and gain vigilance until end of turn.
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Arsenal Curator gets +1/+1 as long as you control a Plains.
{2}{W}: Untap target creature you control. It gets +0/+1 until end of turn.