msem-instigator

As an additional cost to cast this spell, exile any number of cards from your graveyard. This spell costs {1} less to cast for each card exiled this way.
All creatures get -3/-3 until end of turn.

Deathtouch
Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)

Toxic Jungle enters the battlefield tapped unless you have 15 or less life.
{T}: Add {B} or {G}.

Deathtouch

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

Whenever Toxic Miscreant deals combat damage to a player, that player discards a card.

As Toxic Spring enters the battlefield, you may tap an untapped creature you control. If you don't, Toxic Spring enters the battlefield tapped.
{T}: Add {U} or {B}.

Enchant creature you control
Whenever a land enters the battlefield under your control, put a +1/+1 counter on enchanted creature.
{3}{G}, Sacrifice Trace the Oasis: Draw cards equal to enchanted creature's power.

Equipped creature gets +0/+2.
When equipped creature dies, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Equip {1}

Enchant creature
Enchanted creature has hexproof.
{U}: Enchanted creature can't be blocked by target creature this turn.

Untap target creature. It gets +2/+2 and gains hexproof until end of turn.

Search your library for a creature card, reveal it, then shuffle and put that card second from the top.

Target creature you control fights target creature you don't control, then fights it again.

Flash
When Trade Route Bandit enters the battlefield, you may have each player draw two cards.

Frenzy 1 (Whenever this creature attacks and isn't blocked, it gets +1/+0 until end of turn.)
Whenever Trading Traitor deals combat damage to a player, you lose life equal to the number of unblocked attacking creatures you control and draw that many cards.

(As this Discovery enters and after your draw step, add a progress counter. Stop after you've discovered.)
I, II — Mill two cards. You gain 2 life. (Put the top two cards of your library into your graveyard.)
Discovery — During each of your turns, you may cast a permanent spell from your graveyard.

You draw a card, lose 2 life, then create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

Rapport — Whenever Trae, Serpent's Grasp and at least one other creature you control become tapped, each player draws a card. Then Trae, Serpent's Grasp deals 2 damage to each opponent with four or more cards in hand.

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
{2}{W}{W}, Return an unblocked attacking creature you control to its owner's hand: Create a 4/4 white Angel creature token with flying that's tapped and attacking.

For each player, you choose from among the permanents that player controls an artifact, a creature, an enchantment, and a planeswalker. Then each player sacrifices all other nonland permanents they control.

Destroy target creature with power less than or equal to the number of creature cards in your graveyard.

Haste
Sacrifice a land: Trail Blazer explores. You may put a basic land card from your hand onto the battlefield tapped. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then you may put that card in your graveyard.)

Tap target creature, then draw X cards, where X is its mana value.

At the beginning of your end step, you may mill a card.
{3}{B}, Exile two cards from your graveyard: Target player loses 2 life.

Put target permanent card from your graveyard on top of your library.