msem-instigator

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
{2}{R}{G}{W}: You may put a creature card from your hand onto the battlefield. It gains haste and vigilance until end of turn. At the beginning of the next end step, return it to your hand unless you're in a renaissance.

[+1]: Each opponent discards a card. If a land card is discarded this way, create a 1/1 colorless Spirit creature token with flying.
[–2]: Until end of turn, creatures you control get +1/+1 and creatures your opponents control get -1/-1.
[–6]: Each opponent chooses up to one permanent they control of each permanent type, then sacrifices the rest.

Draw a card, then reveal any number of creature or land cards from your hand. You gain that much life.

First strike, haste
Wanderlust — At the beginning of combat on each of your turns, if you control four or more differently named lands, you may pay {1}{R}. If you do, create a 4/4 red Dragon creature token with flying and haste. Exile that token at end of combat.

Flying
Once each turn, when an opponent draws a card while they have more cards in hand than you, you may draw a card.

Each player sacrifices a creature. If a player lost 3 or more life this turn, each opponent sacrifices a creature instead.

Profane Emissary gets +2/+2 and has lifelink as long as you control a Demon.
If you would draw a card, you may instead search your library for a Demon card, reveal it, put it into your hand, then shuffle. You lose life equal to that card's mana value.

Target nonland permanent phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)
Draw a card.

{1}{G}: Exile two target cards from a single graveyard. When you do, germinate. (Put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)

Flash
If a card or token would be put into an opponent's graveyard from anywhere, exile it instead.

Exile target instant or sorcery card from your graveyard. Copy it. You may cast the copy. (Cast a copy of this spell once while this creature is on the battlefield.)

Create an X/X green and blue Plant creature token, where X is the number of differently named lands you control.

Prowess

Each player puts the bottom five cards of their library into their graveyard.
Fuse (You may cast one or both halves of this card from your hand.)

Whenever High-Priestess Nebti attacks or blocks, create a 2/2 white Cat creature token.
{1}{R}{R}, Tap an untapped Cat creature you control: That creature fights target creature you don't control.

Each player sacrifices a creature and discards a card.
Fuse (You may cast one or both halves of this card from your hand.)

Choose one —
• Exile target player's graveyard.
• Target player sacrifices a creature.

Return target creature card with mana value 3 or less from your graveyard to the battlefield. Put a +1/+1 counter on it. It gains indestructible until end of turn.

Concord — This spell costs {4} less to cast if there are four or more card types among permanents you control.
Vigilance, trample, lifelink, haste

Target creature gets +2/+1 and gains trample until end of turn. Create a tapped Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Whenever you make first contact, Abrasive Citizen gets +3/+0 until end of turn. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Abyss Howler must be blocked if able.
Whenever Abyss Howler becomes blocked, defending player loses 2 life and you gain 2 life.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Abyssal Accuser must be blocked if able.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
When Abyssal Familiar dies, it deals 1 damage to you and to any target.

When Abyssal Pact enters, you draw two cards and each player loses 2 life.
Players can't gain life.
Damage can't be prevented.