msem-instigator

{T}: Add {C}.
{1}, {T}, Sacrifice Perilous Passage: Destroy target nonbasic land. Activate only if an opponent controls four or more lands.

Look at the top eight cards of your library. You may reveal up to one Elf and up to one Dwarf card from among them. Put the revealed cards into your hand and the rest on the bottom of your library in a random order. Tenuous Alliance deals 2 damage to you.

You may cast target instant or sorcery card from your graveyard this turn. If that spell would be put into your graveyard, exile it instead.

Flash
When Dehmi, Origin Seeker enters, counter target spell an opponent controls unless that spell's controller has you create X 1/1 red Elemental creature tokens, where X is that spell's mana value.

Whenever you cast a noncreature spell, you may pay {U}. If you do or the spell was cast from your graveyard, draw a card.

Gain control of target nonland permanent. The player that controlled it creates a 3/3 blue Squid creature token.

Flying, vigilance
Prevent all damage Merciful Yuroda would deal to creatures.

Vanishing 3 (This permanent enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Whenever a time counter is removed from Burning Heels, exile the top card of your library. Until end of turn, you may play that card.

If a player taps a nonbasic land for mana, that land produces {C} instead of any other type.
Whenever Rylei Wakebreaker attacks, it and another target creature you control each get +1/+0 until end of turn for each attacking creature you control.

Destroy all creatures without flying.

Double each number and amount of target instant or sorcery spell, activated ability, or triggered ability. Its controller may choose new targets for it. (Amounts are number words, X values, and “a” or “an” used as 1.)

Whenever you cast a spell from exile, you may draw a card.
At the beginning of your upkeep, you may reveal the top card of your library.

Each creature has haste and “At the beginning of combat on your turn, choose an opponent at random. This creature attacks that player this combat if able.”

You may activate loyalty abilities of Xirix, the Usurper during extra turns any time you could cast an instant.
[+1]: Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
[–2]: Destroy each nonland, non-Xirix permanent with the greatest mana value among non-Xirix permanents on the battlefield.
[–6]: Put target permanent card from a graveyard onto the battlefield under your control.

Whenever a creature token you control deals combat damage to an opponent, it deals that much damage to each other opponent.
At the beginning of combat on your turn, you may sacrifice another creature. If you do, create a 2/2 red, white, and black Knight creature token with haste.

Noncreature spells you cast cost {1} more to cast.
Noncreature spells your opponents cast cost {1} more to cast unless that player controls more creatures than you.

{T}: Add {C}. Activate only if you have less life and control fewer creatures than each opponent.

Prowess
Curse spells you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Whenever you cast a Curse spell, you may draw a card.

This spell costs {G} less to cast if it targets a blue or black permanent.
Destroy target artifact, enchantment, or planeswalker.

Add three mana of any one color.

Poisonous 3 (Whenever this creature deals combat damage to a player, that player gets three poison counters.)
When Soulbreaker of Mautakesh enters, target poisoned player sacrifices a creature.

Oshiruko Whisperwalker can't be blocked except by Rogues.
Whenever a creature is returned to its owner's hand, you may draw a card. If you do, discard a card.

Up to X target creatures gain winnow until end of turn. (Damage dealt to a creature with winnow also causes its controller to lose that much life.)
Rain of Ruin deals 2 damage to each creature.

For each land you control, you may return a land card from your graveyard to the battlefield tapped.

Target creature gets +2/+0 until end of turn and can't be blocked except by three or more creatures this turn.
Flashback {U/R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)