msem-instigator

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

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

Search your library for a land card, put it onto the battlefield tapped, then shuffle.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, untap that land.

Enchant creature you control
Whenever a land you control enters, 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.

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.”)

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.

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.

At the beginning of your upkeep, you may return a nontoken creature you control to its owner's hand. If you do, create a 2/2 green Elk creature token.

Whenever a nonland permanent enters under an opponent's control this turn, gain control of that permanent until the end of your next turn. It gains haste until end of turn.

At the beginning of your end step, choose any number of permanents and/or players, then give each another counter of each kind it already has.
[+1]: Scry 1. Add {U} or {R}.
[–X]: Exile the top X cards of your library. Until end of turn, you may play a card exiled with Trainee Karina Oblay.

Vanguard — Whenever a creature you control attacks alone, draw a card.

Rouse 2. Target permanent you controls fights target creature you don't control if both are creatures. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

Each creature you control enters with an additional +1/+1 counter on it.
When Training Sim enters, create a Function token with “Target creature you control fights target creature you don't control.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Equipped creature gets +2/+2 and has hexproof and vigilance.
Equip {2}

When you cast this spell, copy it for each player that has 8 or less life. (The copies have the same target.)
Traitor's Execution deals 3 damage to target player.

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.)
{2}, Discard your hand: Unlock Traitor's Gambit. If the revealed card is red, put it into your hand. Otherwise, put it on top of your library.