msem-instigator

Trample, haste
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.)
At the beginning of the end step, sacrifice Purgator of Storms.

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Whenever you attack, Purphoros deals 1 damage to any target.
{3}{R}: Discard up to two cards, then draw that many cards.

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.

You may have Reaping Willow assign its combat damage as though it weren't blocked.
{2}{G}: Reaping Willow gains indestructible until end of turn.

Trial 6 (As you cast this spell, an opponent of your choice may pay 6 life. If they don't, they fail the trial.)
Flying
When Reckoner of Man enters, if the trial was failed, it deals 3 damage to each creature you don't control.

As an additional cost to cast this spell, pay {2} or sacrifice a creature.
Menace

Trample
When Remnant of the Wild enters, if you cast it, untap all lands you control.

Persist (When this 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.)

Ward {2}
When Rewriter of Flesh enters, target creature you control becomes an enchantment and loses all other card types. (It still has its abilities, but it's no longer a creature.)

Flying, menace
When Riftkeeper Entity enters, discard your hand, then draw cards equal to the number of differently named lands you control.
{1}{R}, Discard Riftkeeper Entity: Create a tapped colorless land token named Fading Rift with “{T}, Sacrifice this land: Add one mana of any color.”

Return target permanent to its owner's hand.
Coalesce {7}{U} (You may cast this from your graveyard for {7}{U}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Trample
Risti Assault Squadron can't attack unless all other creatures you control also attack. (It can attack if it's the only creature you control.)

You may play this card transformed.
Trample

Trample, haste
When Sahra, the Consuming enters or attacks, sacrifice a permanent.
At the beginning of your end step, transform Sahra unless you've sacrificed two or more permanents this turn.

You may sacrifice three artifacts rather than pay this spell's mana cost.
Exile three artifact cards from your graveyard: Return Salvage Titan from your graveyard to your hand.

Flying
Whenever Scavenging Hilakites attacks, you may sacrifice another creature. When you do, Scavenging Hilakites deals damage equal to the sacrificed creature's power to any target.

As Scavenging Sandwurm enters, choose decay or remain.
When Scavenging Sandwurm dies,
• Decay — Draw a card.
• Remain — Create a 2/2 black Zombie creature token.

This spell can't be countered.
Flying, protection from cryptic
Whenever you cast a cryptic spell, cast a Sphinx spell, or draw a card, investigate.
{T}, Sacrifice ten Clues: You win the game.

Whenever Shah's Caravan attacks, creatures you control get +1/+1 until end of turn. If you control three or more Satrapies, creatures you control can't be blocked by creatures with power 2 or less this turn.
Satrapycycling {2} ({2}, Discard this card: Search your library for a Satrapy card, reveal it, put it into your hand, then shuffle.)

When Shardsong Seedling enters, conjure two cards named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

Flying, haste
Whenever Shimmering Dragon attacks, for each creature you control, create a tapped and attacking token that's a copy of that creature. Exile the tokens at the beginning of the end step.

Sire of the Shapeless costs {3} less to cast as long as you control three or more creatures.
Trample, haste
{G}, Reveal Sire of the Shapeless from your hand: Create a 1/1 colorless Human creature token. Shuffle Sire of the Shapeless into your library. Activate only as a sorcery.

When Sire of the Wild enters, reveal the top four cards of your library. You may put a creature card from among them onto the battlefield. Shuffle the rest into your library.

Protection from colored spells
{5}{C}{C}: Exile target colored permanent.
{5}{C}{C}, Exile Soul of Muetar from your graveyard: Exile target colored permanent.

Trample
Whenever a creature dealt damage by Sovereign of Old Lovi this turn dies, put a +1/+1 counter on Sovereign of Old Lovi.