msem-instigator

At the beginning of your upkeep, draw a card and reveal it. You lose life equal to that card's mana value unless you control an Eve planeswalker.

Whenever a land you control becomes a creature, put a +1/+1 counter on it.
{2}{G}{U}: Target land you control becomes a 3/3 Elemental creature in addition to its other types until end of turn.

Flying, haste
Whenever Emissary of Antiquity deals combat damage to a player, you may cast an instant or sorcery spell with mana value 3 or less from your hand without paying its mana cost.

When Student of Secrets enters, fateseal 1. (Look at the top one cards of an opponent's library, then put any number on the bottom and the rest on top in any order.)

Target player draws X cards and loses X life.

Destroy target artifact.
Cycling {1}{R} ({1}{R}, Discard this card: Draw a card.)

Whenever Failed Martyr attacks, each other attacking creature gets +1/+0 until end of turn.
Attain {4}{W} ({4}{W}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Rhapsody {4}{R}{W} (Pay {4}{R}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Lifelink, haste

Colossal 2—{4}{B}{B} (You may cast this for its colossal cost to have it enter with two +1/+1 counters; or pay {4}{B}{B} as a sorcery: Put two +1/+1 counters on it if it has none.)
Menace
When Wretched Catoblepas's colossal ability puts one or more counters on it, each opponent sacrifices a creature.

At the beginning of your upkeep, you may pay {B}. If you do, return a Wizard card from your graveyard to your hand.

Deathtouch
When Shadowed Apostle dies, draw a card.

{T}: Add {C}.
{3}, {T}: Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Flying (This creature can't be blocked except by creatures with flying or reach.)
Escorted Rider gets +1/+1 as long as you control another creature with flying.

Target opponent discards a card. If they can't, draw a card. (Then exile this card. You may cast the creature later from exile.)

Destroy target creature with flying. You may put a land card from your hand onto the battlefield.

Target creature you control fights target creature you don't control.
Flashback {5}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

{3}{G}: Put a +1/+1 counter on Lifecaller Dryad.

Ward {2}
As long as you control six or more lands, Frondpond Errand-Runner gets +2/+0 and can't be blocked.

The Urchin King's power and toughness are each equal to the number of cards in all graveyards.
Sacrifice a creature: The Urchin King gains lifelink and indestructible until end of turn.

{2}: Add one mana of any color.

{2}{B}, Sacrifice Determined Slayer: Exile up to three target cards from target player's graveyard. They lose that much life.

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

Destroy target artifact or enchantment.
Draw a card.

Wild Realms enters tapped unless you control two or more other lands.
{T}: Add {G}.
{T}, Pay 1 life: Add {R} or {W}.

Flying
Whenever you attack with three or more creatures, exile the top card of your library. You may play that card until you exile another card with Zarthane, Scourge of Galdurheim.
{2}{B/R}: Target creature gets +1/+0 and gains menace until end of turn. Activate only as a sorcery.