msem-instigator

At the beginning of your upkeep, germinate. Then if creatures you control have total power 10 or greater, transform Mushroom Merchant. (To germinate, put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)

Whenever a creature you control dies, you may put a +1/+1 counter on target creature you control.

Flash (You may cast this spell any time you could cast an instant.)
When Bloodhunter Orca enters, target opponent sacrifices a creature that was dealt damage this turn.

Equipped creature gets +1/+1.
As long as equipped creature is a Warrior, it has first strike.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Flash
Poisonous 2 (Whenever this creature deals combat damage to a player, that player gets two poison counters. A player with ten or more poison counters loses the game.)
When Sankataar Ambusher enters, if an opponent is poisoned, Sankataar Ambusher gets +2/+2 until end of turn.

When Raikai Seafarer enters, you may search your library for up to three cards named Raikai Seafarer, reveal them, put them into your hand, then shuffle.

This spell costs {2} less to cast if you control a Scout.
Search your library for up to two basic land cards, reveal those cards, and put one onto the battlefield tapped and the other into your hand, then shuffle.

Mill three cards. Return a card from among the milled cards to your hand. Then shuffle three cards from graveyards into their owners' libraries.

Look at the top four cards of your library. You may put a land card from among them onto the battlefield tapped. Put the rest into your graveyard.

Enchant creature
Enchanted creature gets -X/-X, where X is the number of creature cards in your graveyard.

Whenever you cast an instant or sorcery spell, look at the bottom card of your library. You may manifest it. If you don't, put it into your hand. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

If a creature entering under you control causes an ability to trigger, you may pay -1. Whenever you do, copy that ability. You may choose new targets for the copy.
[+1]: Exile target creature. Return that card to the battlefield tapped under its owner's control at the beginning of the next end step. If you don't control it, it enters with a stun counter.
[–2]: Draw a card and gain 2 life.

Vigilance
Creature spells you cast cost {2} less to cast.
Other creatures you control can't attack or block.

As Angelic Barracks enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {U}, {R}, or {W}.

At the beginning of your upkeep, discard your hand.
{2}: Greater Masticore deals 1 damage to each other creature.
{6}, Exile six other cards from your graveyard: Return Greater Masticore from your graveyard to the battlefield tapped.

{1}{B}, Sacrifice another creature: Draw a card and 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.”)
{2}{B}, Sacrifice three Idols: Return Demon of Hubris from your graveyard to the battlefield. Activate only as a sorcery.

Untap target creature you control. It gets +1/+4 and gains hexproof and reach until end of turn.

Hexproof
When Elusive Devout enters, choose one —
• Put a +1/+1 counter on Elusive Devout.
• Create a colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”

Enchant land you don't control
Whenever enchanted land becomes tapped, you may draw a card.

Target creature you control deals damage equal to its power to target creature you don't control. Scry 1.

Dominik's Shack enters tapped.
When Dominik's Shack enters, you may mill two cards.
{T}: Add {B} or {G}.

When Dunesea Merchant enters, tap up to X target creatures, where X is the number of Satrapies you control.
Satrapycycling {2} ({2}, Discard this card: Search your library for a Satrapy card, reveal it, put it into your hand, then shuffle.)

Lifelink
Whenever a creature without a bounty counter on it dies, you may pay 1 life. When you do, post a bounty on target creature. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)

Double strike, menace
{R}{W}, Exile Picturesque Champion from your graveyard: Target creature you control gains double strike and menace until end of turn. Activate only as a sorcery.