msem-instigator

When Scrollmaster dies, you may exile it. If you do, search your library for an instant or sorcery card with mana value 4 or less and cast it without paying its mana cost. If you searched your library this way, shuffle.

Creatures you don't control get -1/-1.
Mirage {1}{B} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Enchant creature
Enchanted creature gets +1/+0.
Whenever enchanted creature attacks, target creature can't block this turn.

Shimmer (Whenever this creature attacks, create a tapped and attacking token that's a copy of it. Exile the token at the beginning of the end step.)
{2}{G}, {T}: Create a token that's a copy of target creature token.

Flying, haste
{R}: Varagan Wyrmling gets +1/+0 until end of turn. Activate this ability only up to three times each turn.

Voidtouched Nightblade can't block.
Simulacrum (When this creature dies, exile it from your graveyard. If you do, create a token that is a copy of it except it is a colorless 1/1 Crystal Elf Rogue artifact creature.)

Destroy target creature that's not enchanted and isn't an enchantment.

Creatures your opponents control get -1/-1 until end of turn. (Then exile this card. You may cast the creature later from exile.)

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
Abandon Life and Hope deals 5 damage to target creature or planeswalker.

Menagerie — {1}{G}: Slipsand Hornshell gains indestructible until end of turn. Tap it. Activate only if there are five or more creature types among creatures you control.

Encourage ({T}: Another target creature you control gets +1/+1 until end of turn. Encourage only as a sorcery.)
Whenever a creature deals combat damage to a player, if it was encouraged by Unbeholden Navigator this turn, draw a card.

As Rhythm of Danaj enters, choose Martoob or Tamaak.
• Martoob — At the beginning of your end step, return a nonland card at random from your graveyard to your hand.
• Tamaak — At the beginning of your end step, you may sacrifice a creature. If you do, draw cards equal to its power.

Creatures can't attack you or planeswalkers you control unless their controller pays {X} for each of those creatures, where X is the number of attacking creatures.

Target creature you control deals damage equal to its power to another target creature.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast a noncreature spell, you gain life equal to its mana value.

Flash
Poisonous 2 (Whenever this creature deals combat damage to a player, that player gets two poison counters. A player with ten or more poison counters loses the game.)
When Sankataar Ambusher enters, if an opponent is poisoned, Sankataar Ambusher gets +2/+2 until end of turn.

Enchant opponent
Whenever enchanted player is attacked, you may discard a card. If you do, draw a card.

Destroy target creature or planeswalker. Create a Treasure token.

As long as you control three or more creatures with the same name, Scouts and Wizards you control can't be blocked.
A deck can have any number of cards named Ch'aska Walla Chasqui.

Spawn of Andazir enters with X +1/+1
counters on it.
Lionize {2}{G} ({2}{G}, Exile this card from your hand:
Put a +1/+1 counter on target creature and it gains the following ability until end of turn. You may cast this card on a later turn from exile.)
Whenever this creature deals damage to a player or noncreature permanent, double the number of +1/+1
counters on it.

Whenever a land you control enters, upgrade target creature. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• Vigilance
• Trample

This spell costs {1} less to cast for each creature that attacked this turn.

Lands you control have “{T}: Add one mana of any color.”
{T}: Add one mana of any color.

Menace
When Rallios Unleashed enters, create a 2/2 black Zombie creature token.
Whenever Rallios Unleashed deals combat damage to a player, create a 2/2 black Zombie creature token for each creature card in your graveyard.

Flying
{3}{W}: Scry 2. You gain 2 life.