msem-instigator

Enchant opponent
When Lost Knowledge enters, enchanted player reveals their hand.
{1}, Sacrifice Lost Knowledge: Scry 2, then draw a card.

{G}{U}: Glacier Tortoise gets +5/-5 until end of turn. Activate only once each turn.

Scoured Mesa enters tapped.
{T}: Add {W}.
Desertcycling {1}{W} ({1}{W}, Discard this card: Search your library for a Desert card, reveal it, and put it into your hand, then shuffle.)

Silent Hunt deals 3 damage to target creature and you gain 3 life.
Forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

Changeling (This card is every creature type.)
{1}: Another target creature you control gains the creature type of your choice until end of turn.
{1}: Change the text of another target creature you control by replacing all instances of one creature type with the creature type of your choice until end of turn.

You gain life equal to the greatest power among creatures you control and cards in your graveyard.
Draw a card.

Indestructible
As long as your devotion to green and white is less than seven, Karametra isn't a creature.
You may play an additional land on each of your turns.
As you begin searching your library, you may reveal a basic land card from your library and put it into your hand.

{T}: Add {C}. Spend this mana only to cast a creature spell.
{T}, Sacrifice Waypoint Stone: Choose target creature card in your graveyard that was put there from the battlefield this turn. Return it to your hand.

Equipped creature has double strike.
Whenever equipped creature attacks, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Abilities of Idols you control that target equipped creature cost {1} less to activate.
Equip {2}{W}

As Mercantile Accords enters, choose a number.
Whenever an opponent casts a spell with the chosen mana value, you draw a card and create a Treasure token.

When Ancestor's Skull enters, target creature gets +1/+0 and gains menace until end of turn.
{2}, Sacrifice Ancestor's Skull: Target creature gets +2/+0 and gains menace until end of turn.

Lifelink
Creature and Aura cards with mana value 3 or less in your graveyard have revive {2}{W/B}. ({2}{W/B}, Exile that card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Flash
Defender, flying

Primal {R} (During your turn, you may cast this spell for {R} instead of playing a land.)
Target creature gets +4/+0 and gains trample until end of turn.

When Dark Ascension enters, if you cast it, all creatures get -13/-13 until end of turn.
Whenever you cast a black spell, Dark Ascension deals X damage to any target and you gain X life, where X is the number of black mana symbols in that spell's mana cost.

This spell costs {G} less to cast if it targets a blue or black permanent.
Destroy target artifact, enchantment, or planeswalker.

Create a token that's a copy of target permanent you control, except it isn't legendary. Then put Picture Perfect on the bottom of its owner's library if you cast it from exile.
Leitmotif (If you cast this spell from your hand, exile it as it resolves. When you next cast a spell that shares a color with this card, you may cast this from exile without paying its mana cost.)

[+1]: Add {R} or {G}. You can't spend this mana to cast an Elf spell.
[–2]: Winona, the Heretic deals 4 damage to any target. If that target is an Elf, Winona deals 4 damage to that Elf's controller.
[–6]: Until end of turn, any time you could cast an instant, you may pay {R}. When you do, Winona deals 2 damage to any target.

Haste
When Prophetic Flame dies, scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)

Haste
Menace (This creature can't be blocked except by two or more creatures.)
{4}{R}{R}: Ferocious Desert-Hunter gets +X/+0 until end of turn, where X is its power.

Amass Soldiers 2. (Put two +1/+1 counters on an Army you control. It's also a Soldier. If you don't control one, create an 0/0 black Soldier Army creature token first.)
Flashback {3}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

{T}: Add {C}.
{2}: Idravir becomes a 2/2 creature with undying in addition to its other types until end of turn. (When that creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Overgrown Siren must be blocked if able.

({T}: Add {W} or {B}.)
Deserted Steppe enters tapped unless you control two or more basic lands.

Scrap, the Second Myr has all activated abilities of other artifact creatures you control.