msem-instigator

Reach
Concord — Am'atambi's Fangs gets +1/+0 and has deathtouch as long as there are four or more card types among permanents you control.

Enchant creature
Enchanted creature gets +2/+2.
Whenever enchanted creature attacks, if it's a Scout, scry 2.

Flash (You may cast this spell any time you could cast an instant.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Trample
As long as it's an opponent's turn, Ambushing Alligator is a blue Bird with base power and toughness 1/1 and has flying and hexproof.

Reach, vigilance
When Amorphous Tyrant enters, another target creature you control deals damage equal to its power to target creature or planeswalker you don't control.
Evoke {G} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Whenever Ancient Durumderm attacks, you may return another creature you control to its owner's hand. If you do, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Target creature you control gets +3/+3 until end of turn. Then if that creature has power 10 or greater, each other creature you control gets +3/+3 until end of turn.

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.)
{6}: Unlock Ancient Maze. If the revealed card is green, put it into your hand. Otherwise, put it on top of your library.

Ward {3}

When Ancient of the Glade enters, put a +1/+1 counter on each other creature you control.
{2}, Remove a +1/+1 counter from a creature you control: That creature gains indestructible until end of turn.

Reach
Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)
When Angelbane Spider enters, destroy target creature with flying.

{T}, Reveal an Angel card from your hand: For each of that card's colors, add one mana of that color.

Whenever Angeltouched Dryad or another permanent you control is turned face up, add {C}{C}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Whenever another nontoken creature you control enters, create a 1/1 green Saproling creature token.
{1}{G}, {T}: Populate. (Create a token that's a copy of a creature token you control.)

Reach, trample
When Anran, Root Steward enters, destroy up to three target noncreature permanents. For each permanent destroyed this way, its controller creates a colorless enchantment land token named Paradise with hexproof and “{T}: Add one mana of any color.”

Vigilance, trample
Whenever another Horror you control enters, choose one —
• Destroy target artifact or enchantment.
• You gain 4 life.
• Apex Abomination fights another target creature.

At the beginning of your upkeep, if an opponent controls more creatures than you, you may reveal the top seven cards of your library. Target opponent chooses a creature card revealed this way. Put that card onto the battlefield, and the rest into your graveyard.

If this spell was foretold, target player creates a 4/4 red Dragon creature token with flying. Apex's Prey deals damage equal to the greatest power among creatures you control to up to one target creature or planeswalker.
Foretell {1}{R}{R}{G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Target creature you control deals damage equal to its power to target creature or planeswalker you don't control.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

When Apprentice Summoner enters, search your library for a creature card with mana value 1 or less, put it onto the battlefield, then shuffle.

At the beginning of your upkeep, you may pay {1}{G/U}. If you do, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)
At the beginning of your end step, you may pay {1}{G/U}. If you do, populate. (Create a token that's a copy of a creature token you control.)

Target creature you control deals damage equal to its power to target creature you don't control.

This spell costs {1} less to cast for each differently named land you control.
Reach, trample

Trample
When Arborback Stomper enters, you gain 5 life.