msem-instigator

[+1]: You may play an additional land this turn.
[–1]: Discard a card. If you do, return target creature, land or sorcery card from your graveyard to your hand.
[–5]: Create Thrice-Folded Lotus, a colorless Masterpiece artifact token with “{T}: Add three mana of any one color.” and “{3}, {T}: This artifact deals 3 damage to any target.”

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Create a tapped colorless Mountain Forest land token. (It has “{T}: Add {R} or {G}.”)

Vigilance, menace, trample, haste
Whenever you cast a spell, you may consume. If you do, put a +1/+1 counter on Thunderous Avarice. (To consume, sacrifice another creature or exile a creature card from your graveyard.)
Whenever an opponent casts a spell, they may consume. If they don't, put a +1/+1 counter on Thunderous Avarice.

[0]: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
[–2]: Exile target creature. Create a battle token with three defense and “When this battle leaves the battlefield, return the exiled card to the battlefield under its owner's control.” You're protecting it.
[–5]: Create two 0/0 black Phyrexian Germ creature tokens, then put two +1/+1 counters on each creature you control.

Whenever one or more +1/+1 counters are put on a creature you control, you may search your library for a creature card, reveal it, put it into your hand, then shuffle.

Exile target creature an opponent controls. Each player may search their library for a basic land card and put that card onto the battlefield tapped. Then each player who searched their library this way shuffles.

Whenever a nontoken creature you control dies, create a 1/1 black Spirit creature token with flying.
[+1]: Each opponent loses 2 life and you gain 2 life.
[–2]: You may sacrifice a creature. When you do, destroy target nonland permanent.

Return up to two target creature cards with total mana value 3 or less from your graveyard to the battlefield tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Whenever another creature you control enters, target opponent loses 1 life and you gain 1 life.
Sacrifice Somber River Bearer: Creatures you control gain indestructible until end of turn.

Prowess, prowess, prowess
Noncreature spells you cast cost {1} less to cast.

Cosmic Coalescing deals X damage to any target. You may reveal a noncreature card with mana value X or less you own from outside the game and put it into your hand. X can't be 0.
Exile Cosmic Coalescing.

When Paul, Rock Bottom dies, you may discard a card. If you do, return this card from your graveyard to your hand at the beginning of the next end step.
[+1]: Draw a card, then discard a card.
[0]: Until end of turn, Paul becomes a 2/2 Construct creature with prowess. Prevent all damage that would be dealt to them this turn.
[–3]: Return target instant or sorcery card from your graveyard to your hand.

[+1]: Create a tapped 3/3 black Crocodile creature token with menace.
[–1]: You may cast a copy of Size Up.
[–7]: Each land you control becomes a 3/3 Crocodile creature and gains menace and haste until end of turn.

Destroy target nonland permanent with mana value 3 or less. (Then exile this card. You may cast Irbek later from exile.)

Menace
When this creature dies, create two tapped 3/2 colorless Eldrazi creature tokens. Put a stun counter on one of them.

Mill three cards. When you do, return another nonland card from your graveyard to your hand.

At the beginning of your upkeep, exile the top card of your library. If that card has mana value 2 or less, you may play it from exile this turn.
[+1]: Create a 1/1 colorless Servo artifact creature token. If you exiled an artifact or creature card this turn, create two instead.
[0]: Create a Treasure token. If you exiled a card that had a mana ability this turn, create two instead.
[–1]: Comet deals 2 damage to any target. If you exiled an instant or sorcery card this turn, Comet deals 2 damage to any target.

Flash
When Commanding Princess enters, choose two —
• Commanding Princess deals 2 damage to any target and you gain 2 life.
• Return target permanent card with mana value 2 or less from your graveyard to your hand.
• Destroy target artifact or enchantment.
• Create a 1/1 colorless Shapeshifter creature token with changeling.

Whenever one or more creatures you control deal combat damage to an opponent, choose up to that many —
• Create a Weapon token and attach it to one of those creatures. (It's an Equipment with equip {2} and “Equipped creature gets +1/+1.”)
• Add {R}{W} at the beginning of your next main phase.
• Each player draws a card.

Choose one —
• Destroy target artifact or enchantment.
• Return target creature to its owner's hand.
• Draw a card.

[+2]: Until end of turn, Helene Trant becomes a 4/4 Human Warrior creature with hexproof and trample that's still a planeswalker. Prevent all damage that would be dealt to her this turn.
[–2]: Draw two cards.
[–4]: You get an emblem with “Whenever one or more creatures you control deal combat damage to a player, draw a card.”

Draw two cards, then you may put a land card from your hand onto the battlefield. If you cast In Dire Straits during your turn for its reconstruct cost, create X 3/2 green Horror creature tokens, where X is the number of lands you control.
Reconstruct {8}{G}{G}{U}{U} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
{5}: Unlock Key to the Nexus. If {W}{U}{B}{R}{G} was spent to activate this ability, you may cast the revealed card without paying its mana cost. Otherwise, put that card on top of your library.

Flying
Spirited (When this creature enters, you may activate one of its activated abilities without paying its costs.)
{3}{U/B}{U/B}: Look at the top card of target opponent's library, then exile it face down. You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any type to cast that spell.

Spirited (When this enters, you may activate one of its activated abilities without paying its cost.)
{1}, {T}, Discard a card: You gain 4 life.
{2}, {T}, Pay 2 life: Create a 1/1 colorless Construct artifact creature token. It can't block this turn.
{3}, {T}, Sacrifice a permanent: Draw a card.