msem-instigator

Doomsday Horde enters tapped unless it was foreshadowed.
When Doomsday Horde dies, search your library for a card, put it into your hand, then shuffle.
Foreshadow {3}{B}{B}{B} (You may cast this spell for its foreshadow cost. If you do, also trigger its “dies” abilities when it enters.)

Whenever another creature dies, you gain 1 life.
At the beginning of each end step, if you gained 3 or more life this turn, transform Dowager of Traublassen.

At the beginning of your first main phase, add {R}.
Whenever a colossal ability puts one or more counters on a creature you control, Draconic Symphony deals 2 damage to any target.

Exile target creature with power 3 or less. You gain 3 life.

When Dread Elk dies, put a +1/+1 counter on target creature you control. If that creature is a Zombie, put two +1/+1 counters on it instead.
Foreshadow {5}{B} (You may cast this spell for its foreshadow cost. If you do, also trigger its “dies” abilities when it enters.)

Return up to one target creature card from your graveyard to the battlefield tapped. You gain 2 life.
Tether (Then if you cast this from your hand, you may exile it tethered to a creature you control. When it dies, you may cast this from exile without paying its mana cost.)

When Dregscape Wretch dies, create a 2/2 black Zombie creature token.

First strike
{4}{W}, {T}: Target creature gets +2/+1 and gains first strike until end of turn. Activate only as a sorcery.

All creatures get -2/-2 until end of turn. Scry 1.

Menace
Spells you cast from your graveyard cost {2} less to cast.
Whenever Drownyard Captain attacks, if a card left your graveyard this turn, draw a card.

Whenever Drownyard Colossus or another creature you control enters, any number of target players each mill cards equal to that creature's toughness.
{2}{U}{B}, {T}: Draw a card, then create a 0/3 blue Crab creature token with “{T}: Target player mills a card.”

When Druid's Grimoire enters, create two 2/2 green Wolf creature tokens.
{T}: Add {G}.

Defender
When Drunau Egg enters, target player mills two cards.
{3}{U}{U}: Transform Drunau Egg. Activate only as a sorcery and only if an opponent has thirteen or more cards in their graveyard.

Trample

At the beginning of your upkeep, choose one —
• Create a colorless artifact token named Etherium Cell with “{T}, Sacrifice this artifact: Add one mana of any color.”
• Put a +1/+1 counter on another target artifact. It becomes a 0/0 Construct artifact creature if it isn't a creature.

When Earthbreaker Behemoth enters, it deals damage equal to its power to up to one target creature you don't control. Excess damage is dealt to that creature's controller instead.

Flying, haste
Whenever Eavesknocker attacks, another target attacking creature gets +1/+1 until end of turn.

Enchant creature
Enchanted creature has “Whenever this creature deals combat damage to a player, create a token that's a copy of it, except it's a 1/1 Reflection” and “When this creature leaves the battlefield, sacrifice all Reflections you control.”

[+2]: You may discard a card. If you do, draw two cards.
[–3]: Return target creature card from your graveyard to the battlefield. It gains haste. Return it to your hand at the beginning of the next end step.
[–7]: Discard your hand, then draw seven cards. You may put an Edarna planeswalker card from your hand or graveyard onto the battlefield.

Flying, haste
{2}{B}{R}: Return Edarna's Augurling from your graveyard to the battlefield. Return it to your hand at the beginning of the next end step. Activate only as a sorcery.

First strike
Whenever Edgar Markov, Bloodsire attacks, exile the top three cards of your library. You may play those cards until end of turn.
Whenever another Vampire you control enters, it deals damage equal to its power to any target.

Eerie Wildwood enters tapped. When it enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {R} or {G}.

Your opponents can't gain life.
Whenever you cast a noncreature spell, put a +1/+1 counter on Eidolon of the Arena.

{T}: Add {C}.
{4}, {T}, Sacrifice Elgaud Fortress: Create a token that's a copy of target artifact you control. Activate only as a sorcery.

{4}{G}, Sacrifice Elvish Godtracker: Create a 5/5 green Beast creature token.