msem-instigator

At the beginning of each player's upkeep, that player may pay {2} or 2 life. If they don't, they return a permanent they control to its owner's hand.

Whenever Solvent Tide attacks, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

({T}: Add {B} or {G}.)
Somber Marsh enters tapped.

Somber Meadow enters tapped.
{T}: Add {W} or {B}.
{1}, {T}: Add one mana of any color.

Whenever another creature you control enters, target opponent loses 1 life and you gain 1 life.
Sacrifice Somber River Bearer: Creatures you control gain indestructible until end of turn.

You may look at the top card of your library any time.
You may play lands from your graveyard and the top of your library.

Somberwald Rider can't be blocked by creatures with power 2 or less.
{2}{G}: Transform Somberwald Rider. Activate only if it's attacking.

Somberwald Slaughterer can't be blocked by creatures with power 2 or less.
At the beginning of your end step, if Somberwald Slaughterer didn't attack this turn, transform it.

When Something in the Woods enters or at the beginning of your upkeep, Something in the Woods explores. If it explores a creature card, you may have it become a copy of that card. (It loses this ability. To explore, reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this, then you may put that card into your graveyard.)

When Somnambulance enters, each player conjures a card named Fatigue and puts it on top of their library. (It's a colorless sorcery that costs {2} with “Draw a card.”)
Whenever a player casts a spell named Fatigue, you may draw a card. If you do, you lose 1 life.

Enchant permanent
Enchanted permanent is a land with “{T}: Add {G}{W}{U}” and loses all other card types and abilities.
{1}, Discard Song of Shoals: Add one mana of any color. Scry 1.

Enchant creature
Enchanted creature gets +1/+1 for each creature you control.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Whenever a creature you control attacks alone, untap all lands you control.

Defender, reach
When Soothevine Elemental enters, draw a card.

Equipped creature gets +1/+0 for each instant and sorcery card in your graveyard.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

As Sorcerous Spyglass enters, look at an opponent's hand, then choose any card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.

[+1]: Draw a card. Each player loses 1 life.
[–2]: Create two 1/1 black Bat creature tokens with flying and lifelink.
[–3]: Target creature gets -13/-13 until end of turn. You control abilities of that creature that trigger this turn.

Reach
{3}, Exile Sorrowful Seeker from your hand: Draw a card. You may cast this card for as long as it remains exiled.

Enchant creature
When this enchantment enters, you may put a -1/-1 counter on a creature you control. If you do, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

When Sorrowslayer enters, put a +1/+1 counter on target creature.
Remove a +1/+1 counter from Sorrowslayer: Trigger a death knell of a permanent you control. Activate only once each turn and only as a sorcery.

Flying, lifelink
Morph {4}{B}
When Soul Cajoler is turned face up, manifest the bottom card of your library. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Whenever equipped creature attacks or blocks, you gain 2 life.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Menace
Inspired — Whenever Soul Engulfer becomes untapped, each opponent loses 4 life.

{1}, {T}: Exile target card from a graveyard. Scry 1.
{T}, Exile Soul Gate: Exile all graveyards.

When Soul Jar enters, exile target creature and each other creature with the same name as that creature until Soul Jar leaves the battlefield.