msem-instigator

When Master Negotiator enters, you may gain control of target nonland permanent an opponent controls with mana value 2 or less. If you do, its controller may draw a card. Otherwise, you draw a card.

Target creature you control gets +3/+3 and gains lifelink and trample until end of turn.
Inscribe {3}{G}{W} ({3}{G}{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.)

Equipped creature has vigilance and “{T}: Add one mana of any color.”
Equip {1}

{2}{B}, Exile a card from your graveyard: Tomb Creeper gets +2/+2 until end of turn.

Watchkeeper's Retort deals 2 damage to target creature or planeswalker. Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)

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.)
{1}, Sacrifice two Clues: Unlock Hall of Lost Histories and put the revealed card into your hand.

(Spend a different color of mana on each {VP}.)
Moresso, Infuser of Light is all colors.
Hexproof from monocolored
Whenever you cast a spell with four or more mana symbols in its mana cost, add four mana of different colors. This ability triggers only once each turn.

Mountains you control have “{T}: Add {R}{R}.”
[+2]: Exile the top card of your library. You may play that card until the end of your next turn.
[–2]: Conjure six cards named Scorch. Shuffle them and your hand into your library, then draw two cards.

Equipped creature gets +2/+1.
Whenever a creature you control deals combat damage to a player or planeswalker, you may attach Mervin's Armor to it.
Equip {4}

Trample
Avatar of the Groves enters with a +1/+1 counter on it for each land you control.
Landfall — Whenever a land you control enters, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Civilized — At the beginning of your upkeep, if you control an artifact, a creature, and an enchantment, you draw a card and you lose 1 life.

Whenever a permanent you control leaves the battlefield, Second-Day Slayings deals 1 damage to each opponent.

Whenever a land you control enters, you may sacrifice a creature. If you do, each opponent sacrifices a creature.
{2}{B}{G}, Sacrifice a land: Draw a card.

Shuffle any number of cards from your graveyard into your library. You gain that much life.
Draw a card.

Double strike
At the beginning of each end step, if a creature you control died this turn, Tempered Survivor deals 2 damage to each opponent.

Submerge up to two target attacking nontoken creatures an opponent controls. (To submerge a card, exile it, then put it on the battlefield face down under its owner's control as a 2/2 creature.)

Menace
Whenever a land enters, you may search its controller's library for up to three land cards with the same name as that card, put them into that player's graveyard, then that player shuffles.

Haste
Encourage ({T}: Another target creature you control gets +1/+1 until end of turn. Encourage only as a sorcery.)

Flying
Once during each of your turns, whenever you cast a spell from your graveyard, you may draw a card and create a tapped Treasure token.

Whenever you cast a spell during another player's turn, monstrosity 1. (If this creature isn't monstrous, put a +1/+1 counter on it and it becomes monstrous.)

When Aethermancer's Companion enters, aetherize up to two other non-Cat permanents you control. (Create tokens that are copies of each of them, then exile them.)
Recite {5}{W}{U} (You may cast this spell from your graveyard for its recite cost. If you do, exile it when it enters or if it would leave the battlefield.)

Reach (This creature can block creatures with flying.)
When Spider Broodmother dies, create two 1/2 green Spider creature tokens with reach. (This creature can block creatures with flying.)

When Lurking Angler enters, if seven or more cards are in your graveyard, draw a card. Otherwise, mill two cards.

Renown 2 (When this creature deals combat damage to a player, if it isn't renowned, put two +1/+1 counters on it and it becomes renowned.)
Whenever Fortunate Exorcist attacks, if it's renowned, exile up to one target card from defending player's graveyard.

Whenever a token enters, you may have it become a 3/3 green Elemental creature.