msem-instigator

Destroy target creature with no counters on it and no permanents attached to it.

When Thunderwhirl Dancer enters, it gets +X/+X until end of turn, where X is the number of +1/+1 counters among creatures you control. Then it fights up to one target creature.

Defender
A deck can have any number of cards named Dragonwall Fragment.
At the beginning of your upkeep, if you control twenty or more creatures named Dragonwall Fragment, you win the game.

Whenever Toxic Lurker attacks, you may have target creature defending player controls get -2/-1 until end of turn.

When this creature enters, you may sacrifice a creature. If you do, create a 4/4 red Horror creature token with menace.

As an additional cost to cast this spell, discard two cards.
Draw three cards.

As an additional cost to cast this spell, sacrifice a noncreature permanent.
Search your library for a creature card with mana value equal to 1 plus the sacrificed permanent's mana value, put it onto the battlefield, then shuffle.

Enchant player
Whenever enchanted player casts a spell from anywhere other than exile, exile that spell. During that player's next turn, they may cast that card without paying its mana cost.

Whenever you cast a noncreature spell, put a quest counter on Gate to the Beyond.
At the beginning of your upkeep, if there are three or more quest counters on Gate to the Beyond, you draw a card and you lose 1 life. Then if there are six or more quest counters on it, each opponent loses 2 life.

Prevent all damage that would be dealt to target attacking or blocking creature this turn.
Inscribed creature gets +1/+1 and has vigilance.
Inscribe {2}{W} ({2}{W}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

Kicker {1}{G} (You may pay an additional {1}{G} as you cast this spell.)
When Vigorous Tracker enters, if it was kicked, search your library for a land card, reveal it, put it into your hand, then shuffle.

Enchant creature
You choose whether enchanted creature attacks each combat rather than its controller (after its controller chooses which of their other creatures attack. That player still chooses the player or planeswalker it attacks.)

Flash
When Dragonwall Samurai enters, prevent all combat damage target creature would deal this turn.

Reveal cards from the top of your library until you reveal a land card, then put that card onto the battlefield tapped. You may put another card revealed this way on top of your library. Put the rest of the cards revealed this way on the bottom in a random order.

Flying, ward {3}
Whenever you cast a spell from your hand, you may exile target card that shares a type with it from a graveyard. Until the end of your next turn, you may play that card.

Whenever an opponent casts a spell from a graveyard or without paying its mana cost, Piriman Stones deals 5 damage to them.

Aspiring Dragon has flying and haste as long as you control another Dragon.
{2}{R}{R}: Aspiring Dragon gets +3/+0 until end of turn.

{T}: Envious Nereid deals 1 damage to target creature and 1 damage to that creature's controller.

{G}, Tap an untapped Nymph you control: Overgrown Beast gets +2/+2 until end of turn.

At the beginning of your upkeep, choose a creature. Its controller may sacrifice it. If that player doesn't, you gain life equal to its power.

Barren Boneyard enters tapped.
{T}: Add {B}.
{2/B}{2/B}: Barren Boneyard becomes a 2/3 black Elemental creature with deathtouch until end of turn. It's still a land.

Reach
Menagerie — When Canopyctopus enters, if there are five or more creature types among creatures you control, reveal the top card of your library. If its mana value is less than or equal to the number of lands you control, draw a card. Otherwise, you may put that card into your graveyard.

Ignition Point deals 3 damage to any target.
The next card you cast this turn can be cast as though it has flash.

Prowess
When Cramming Student enters, conjure ten cards named Fatigue and shuffle them into your library. (They're colorless sorceries that cost {2} and have “Draw a card.”)
Instant and sorcery spells you cast cost {1} less to cast.