msem-instigator

This spell costs {1} less to cast for each artifact and enchantment you control.
Reveal the top seven cards of your library. Put any number of noncreature, nonland cards from among them into your hand and the rest of the revealed cards into your graveyard.

Flying, menace
When Riftkeeper Entity enters, discard your hand, then draw cards equal to the number of differently named lands you control.
{1}{R}, Discard Riftkeeper Entity: Create a tapped colorless land token named Fading Rift with “{T}, Sacrifice this land: Add one mana of any color.”

This spell costs {1} less to cast for each instant and/or sorcery card in your graveyard.
Once each turn, when you cast an instant or sorcery spell, you may create a 4/4 white Angel Cleric creature token with flying and vigilance.

When Rotting Greatwurm dies, put three +1/+1 counters on target creature you control.
Fleeting {2}{G} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

This spell costs {2} less to cast for each creature that died this turn.
Each player exiles all creature cards from their graveyard, then sacrifices each creature they control, then puts all creature cards they own exiled this way onto the battlefield. Exile Sea of Corpses.

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

[+2]: Exile any number of target artifacts and/or enchantments you control, then return them to the battlefield under your control. You may draw that many cards.
[–4]: Search your library for an enchantment card, put that card onto the battlefield, then shuffle.
[–12]: Put any number of permanent cards you own from outside the game onto the battlefield tapped.

When Shojiro, the Wavewaker enters, submerge up to eight target creatures your opponents control. (To submerge a card, exile it, then put it on the battlefield face down under its owner's control as a 2/2 creature.)

This spell costs {2} less to cast for each face-down creature you control.
Flying

This spell costs {1} less to cast for each poison counter your opponents have.
Poisonous 1 (Whenever this creature deals combat damage to a player, that player gets a poison counter. A player with ten or more poison counters loses the game.)
At the beginning of your end step, each opponent with seven or more poison counters loses the game.

Sire of the Shapeless costs {3} less to cast as long as you control three or more creatures.
Trample, haste
{G}, Reveal Sire of the Shapeless from your hand: Create a 1/1 colorless Human creature token. Shuffle Sire of the Shapeless into your library. Activate only as a sorcery.

When Sire of the Wild enters, reveal the top four cards of your library. You may put a creature card from among them onto the battlefield. Shuffle the rest into your library.

Skavi Behemoth can't be the target of nongreen spells or abilities from nongreen sources.

Trample, haste
When Soul of the Mountain enters, if it isn't a token, for each two Mountains you control, create a token that's a copy of it.

Trample
When Spawn of Qiyan enters, distribute four +1/+1 counters among any number of target creatures you control.
{2}{G}: Put Spawn of Qiyan from your graveyard into your library second from the top.

Whenever this creature enters, attacks, or leaves the battlefield, choose one that hasn't been chosen.
• Return another target nonland permanent to its owner's hand.
• Draw two cards.
• Create three 1/1 blue Bird creature tokens with flying.
• Add {U}{U}{U}{U}. You can't spend this mana to cast creature spells.

When Spirit of the Falls enters, choose a permanent type. Return all other permanents of the chosen type to their owner's hands.
Discard two land cards: Spirit of the Falls gains hexproof until end of turn.

Hexproof
Cycling {3} ({3}, Discard this card: Draw a card.)

Flying, first strike
Whenever Terror of Sunset Cliffs attacks, each player discards their hand and draws seven cards.
Whenever an opponent discards a card, Terror of Sunset Cliffs deals 1 damage to that player.

Menace
When The Duneborn Host enters, mill four cards.
Whenever a card is put into your graveyard from anywhere, each opponent loses 1 life and you gain 1 life.
Whenever a card leaves your graveyard, create a 2/2 black Zombie creature token.

Whenever The Feller of Greatwoods enters or attacks, you may sacrifice two noncreature permanents. For each permanent sacrificed this way, reveal the top five cards of your library. You may put a creature card from among them onto the battlefield and the rest into your graveyard.

Look at the top sixteen cards of your library. Put any number of creature cards with different mana values from among them onto the battlefield and the rest on the bottom of your library in any order.

Flying
You pay {0} to cast your first spell each turn rather than its mana cost. If you cast a spell with {X} in its mana cost this way, X is 8.

Rather than pay the mana cost for a spell, its controller may discard a card that shares a color with that spell.
Whenever an opponent casts a spell, counter that spell unless they pay 5 life.