msem-instigator

Your opponents can't gain life.
Whenever you cast a noncreature spell, put a +1/+1 counter on Eidolon of the Arena.

Whenever a creature attacks, if its toughness is greater than its power, untap it.

{1}{R}: Target creature can't block Slippery Salamander this turn.

Trample, haste, indestructible
Whenever a permanent an opponent controls is put into a graveyard from the battlefield, put a +1/+1 counter on target Ooze.

Haste
Augmented — When Attuned Lifeform enters, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on each creature you control. They gain vigilance until end of turn.

{T}: Add {C}.
Whenever you tap Primal Channeler for mana, the next creature spell you cast this turn can be cast as though it had flash.

When Uncovered Secrets enters, search your library for an artifact card, reveal that card, then shuffle and put that card on top.
Concord — Creatures you control get +1/+1 as long as there are four or more card types among permanents you control.

Whenever a token creature you control dies, each opponent loses 2 life.

Outer Wall Guard enters with a +1/+1 counter on it if you gained life this turn.

Surveil 2, then draw three cards. (To surveil 2, look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Target creature gets +X/+X and gains trample until end of turn, where X is the number of lands you control.
Fabled {4}{R}{G} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that creature.)

Flash
If a player would conjure a card, they instead conjure a card named Data-Point. (It's a sorcery that costs {2} with “Draw a card.”.)
If a player would copy a spell or cast a copy, they copy the card named Data-Point instead of anything else.

Flash
Flying, vigilance
When Henrick enters, exile target spell. For as long as that card remains exiled, its owner may play it without paying its mana cost.
Spells players cast from anywhere but their hands cost {X} more to cast, where X is the number of creatures with flying you control.

When Compose from Dreams enters, you may cast any number of cards named Fatigue from your hand and graveyard without paying their mana costs.
Whenever you cast a spell, each opponent loses 1 life. Then you may draw a card if that spell wasn't cast from your hand. Then add {U}{B}{R} if you don't own that spell.

You have no maximum hand size.
{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Greenheart Den enters tapped.
{T}: Add {G}.
{G}, {T}: Target creature you control gets +1/+1 until end of turn. Activate only as a sorcery and only if you control a green creature.

Koth's Retaliation deals 4 damage to target creature. When that creature dies this turn, exile its controller's graveyard.

{T}, Discard a card: Draw a card.
{1}, {T}, Discard a card: Scry 2, then draw a card.
{4}, {T}, Discard a card: Search your library for a card, put it into your hand, then shuffle.

Boneyard Pass enters tapped unless you control a basic land.
{T}: Add {W} or {B}.

Whenever you cast a creature spell, create a 2/1 white Sand creature token with flying.
Whenever you cast an instant or sorcery spell, create a 3/1 red Sand creature token with haste.
Whenever you cast an enchantment or artifact spell, create a 2/2 blue Sand creature token with hexproof.
Whenever a land you control enters, create a 3/3 green Sand creature token.

[+1]: Untap target land.
[–1]: Exile the top card of your library. You may play that card until end of turn. If a land card is exiled this way, you gain 2 life.
[–7]: Untap each land you control. Lands you control become 3/3 Elemental creatures with haste until end of turn. They're still lands.

Overgrown Ruins enters tapped.
As Overgrown Ruins enters, choose a color other than green.
{T}: Add {G} or one mana of the chosen color.

Until end of turn, gain control of target creature and it gains haste. Untap it.
Fuse (You may cast one or both halves of this card from your hand.)

You may change the targets of target instant spell, sorcery spell, or activated ability.

Once each turn, when you foretell a card or cast a foretold spell, you may create a 1/1 blue Rogue creature token.
{1}{U}{B}: Draw a card, then discard a card.