msem-instigator

At the beginning of your upkeep, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
{5}{W}{W}, Sacrifice three Idols: Return target creature card from your graveyard to the battlefield with three +1/+1 counters on it.

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

Flash
Flying
When Powder Scatterer enters, exile target noncreature spell. Its controller draws a card.

Target player discards two cards.
Kindle 2—{1}{B}{B} ({1}{B}{B}, Exile this card from your graveyard: Create two 1/1 colorless Elemental creature tokens. Kindle only as a sorcery.)

Flash
When Zhedina Coastguard enters, you may have any number of creatures you control have base power and toughness 1/3, 2/2, or 3/1 until end of turn.

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Master of Ancient Ways mentors a creature, that creature gains double strike until end of turn.

Whenever an Aura you control enters, draw a card.
You may cast Aura spells from your graveyard if that card wasn't put into your graveyard this turn.

Prowess
Whenever Siv Katari, Rebel Technician attacks, create a tapped and attacking X/X colorless Construct artifact creature token with prowess, where X is Siv Katari's power. Exile that token at end of combat.

{T}: Target attacking or blocking creature gets +1/+1 until end of turn.

When Stoic Observation enters, mill two cards, then you may return a creature card from your graveyard to your hand.
{3}{G}, Exile a creature card from your graveyard: Create a 2/2 green Wolf creature token. You gain 2 life.

Lifelink, menace

Renegade Spellweaver can't be blocked as long as you've foretold a card or cast a foretold spell this turn.

{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.

Reflections you control get +2/+2 until end of turn. Other creatures you control get +1/+1 until end of turn.

Flying
Whenever a creature attacks you or a planeswalker you control, put a -1/-1 counter on that creature.

Haste
When Inferno Forerunner enters, you may have target creature gain haste until end of turn.

When Raving Brigand enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)
Whenever you sacrifice an Omen, target player mills three cards.

Creatures your opponents control enter tapped.
Bulwark — At the beginning of each upkeep, if you control a creature with toughness 4 or greater, Danuri Custodian gains indestructible until end of turn.

Wild Peak enters tapped unless you have 15 or less life.
{T}: Add {R} or {G}.

At the beginning of your end step, mill two cards. Then if ten or more cards are in your graveyard, transform Bitter Duckling.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
You don't lose unspent red mana as steps and phases end.
I, II — Add {R}{R}.
III — Create a 3/3 red Phoenix creature token with flying, haste, and “{R}: This creature gets +1/+0 until end of turn.”

First strike
Other Harpies you control get +1/+1 and have first strike.
Whenever a Harpy you control dies, put a +1/+1 counter on Moonlight Stalker.

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever a creature you don't control blocks, it gets -1/-0 until end of turn.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever Flamecloaked Artisan attacks, exile the top card of your library. If it's a nonland card with mana value less than Flamecloaked Artisan's power, you may cast it this turn, and you may cast it as though it had flash.

Harmony — Warriors you control get +1/+0 and gain menace until end of turn.
Whenever Aleud Warcaller attacks, harmonize. (Trigger up to one harmony of a permanent you control.)