msem-instigator

Double strike, vigilance, lifelink

Strange Harbor enters the battlefield tapped unless you have 15 or less life.
{T}: Add {U} or {R}.

Whenever Student of Winds attacks, upgrade target attacking creature. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• Flying

Glitch {3}{W} (Remove one [restriction] for each time you pay the glitch cost.)
Exile target nonland permanent. [Return it to the battlefield under its owner's control at the beginning of the next end step.]

Equipped creature has vigilance and “{T}: Add one mana of any color.”
Equip {1}

Whenever Swift-Fingered Sneak enters the battlefield or attacks, you may discard a card. If you do, draw a card.

[+2]: Up to one target creature gets -1/-1 until your next turn. Tap it. You may remove all counters from it.
[–2]: Destroy target creature with no counters on it.
[–10]: Each opponent's life total becomes equal to the number of creatures they control.

Flying
Other creatures you control with flying get +1/+1.

Thalassic Borough enters the battlefield tapped unless you have 15 or less life.
{T}: Add {U} or {B}.

If you would look at or reveal one or more cards of a library, you may first search that library for that many cards, shuffle that library, then put those cards on top of it in any order.

Equipped creature gets +2/+0 and has deathtouch.
Equip Rogue or Assassin {1}
Equip {3}

Flash
When Thornweald Cavalier enters the battlefield, target creature gets +1/+1 until end of turn. Put a reach counter on it.

Put target nonland permanent into its owner's library second from the top.

{2}{B}, Exile a card from your graveyard: Tomb Creeper gets +2/+2 until end of turn.

{1}{W}, Sacrifice Town Elder: Return target artifact or enchantment card from your graveyard to your hand.

Toxic Jungle enters the battlefield tapped unless you have 15 or less life.
{T}: Add {B} or {G}.

Choose X. You may choose the same mode more than once.
• Each opponent loses 3 life and you gain 3 life.
• Each opponent sacrifices a nonland permanent and you create a Treasure token.
• Each opponent discards a card and you draw a card.

Each player sacrifices two creatures, then gains 2 life and draws a card for each creature they sacrificed this way.

Whenever Twitchy Pyromancer enters the battlefield or attacks, it deals 1 damage to any target. Whenever a creature dealt damage this way dies this turn, upgrade Twitchy Pyromancer. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• Menace
• Prowess

Spend only mana produced by Treasures to cast spells.
{2}, Discard a card: Create two Treasure tokens.

When Undying Lich dies, create a 6/3 black Zombie Horror creature token with menace and “When this creature dies, create an 8/5 black Elder Demon Horror creature token with flying, deathtouch, and menace.”

Unending Slime enters the battlefield with X +1/+1 counters on it.
{2}{G}{G}{G}: Return Unending Slime from your graveyard to your hand.

Gain control of target creature with power less than or equal to the number of different creature types among creatures you control.

Counter target spell if four or more mana was spent to cast it.

All creatures get -2/-2 until end of turn. Add {B}{B}.