msem-instigator

Haste
{T}, Discard a card: Flip a coin. If you win the flip, draw two cards. Otherwise, you may pay {R}. If you do, repeat this process.

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.

Whenever Trusted Comrade and at least one other creature attack, create a 1/1 white Soldier creature token that's tapped and attacking.

Vithian Arcanist gets +2/+0 and has haste as long as you've cast an instant or sorcery spell this turn.
When Vithian Arcanist enters, add {U}{B}{R}. Spend this mana only to cast instant and/or sorcery spells.

{2}{R}: Creatures you control get +1/+0 until end of turn.
{1}{G}: Creatures you control gain trample until end of turn.

When Yamisaran Guard enters, create a colorless Equipment artifact token with “Equipped creature gets +1/+1” and equip {1}.

When Adept of Rations enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Tokens you control have “{2}, {T}, Sacrifice this token: You gain 3 life.”

Whenever Agent of Vitu-Ghazi deals combat damage to a player, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Whenever a creature token you control enters, put a +1/+1 counter on target creature you control.

Reach
When Automated Overwatch enters, create a Function token with “If this spell would create one or more tokens, it creates twice that many of those tokens instead.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Reach, trample
If a +1/+1 counter would be put on another creature you control, instead put a +1/+1 counter on that creature and on Avatar of the Natural.

When Babyscale Bruiser enters, you may reveal a creature card from your hand. If you do, Babyscale Bruiser deals damage to target creature an opponent controls equal to the revealed card's power. That creature deals damage equal to its power to Babyscale Bruiser.

Deathtouch
Whenever a creature dealt damage by Barbed Beast this turn dies, transform Barbed Beast.

Deathtouch
{T}, Sacrifice another creature: Add two mana of any one color.

When Canopy Ratstalker enters, look at the top three cards of your library. You may reveal a land card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Reach
When Chaparral Hunter enters, if a permanent you controlled died this turn, draw a card and you gain 3 life.

Primal {G} (During your turn, you may cast this spell for {G} instead of playing a land.)
When Charging Nymph enters, it gets +2/+0 and gains haste until end of turn.

Vigilance
Whenever Cohorts of the Grove deals combat damage to a player, if you control a creature with power 4 or greater, draw a card.

When Convocation Elder enters, create two 1/1 green Elf creature tokens.
{1}{G}, Discard Convocation Elder: Create a 1/1 green Elf creature token. Draw a card. Activate only as a sorcery.

Spells your opponents cast that target Danithra Muckbruiser cost {2} more to cast.
Danithra Muckbruiser gets +X/+X, where X is the number of cards in your graveyard minus seven. (If there are fewer than seven, it gets +0/+0.)

When Derrivan Brawnmage enters, target creature gets +3/+3 and gains trample until end of turn.

Other Warriors you control get +1/+1.
Whenever one or more Warriors you control deal combat damage to a player, untap all lands you control.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{3}{G}: Mill three cards. Target creature gets +X/+X and gains trample until end of turn, where X is the number of land cards in your graveyard.

Landfall — Whenever a land you control enters, target creature you control gains vigilance until end of turn.

When Endrison Familiar enters, reveal the top four cards of your library. Put all land cards revealed this way into your hand and the rest into your graveyard.