msem-instigator

When Ancestral Council enters the battlefield, search your library for an instant or sorcery card with mana value 2 or less, reveal it, put it into your hand, then shuffle.

This spell can't be countered.
When Auros enters the battlefield, it deals damage to any target equal to your devotion to red. (Each {R} in the mana costs of permanents you control counts toward your devotion to red.)
{R}, Sacrifice Auros, Discard your hand: Draw three cards.

Whenever Crain's Crony enters the battlefield or attacks, reveal the top card of your library and put it into your hand. You lose life equal to that card's mana value.
At the beginning of each end step, if you didn't lose life this turn, you lose the game.

Whenever you cast a noncreature spell, upgrade Embodied Soul. (Give it one of the listed counters it doesn't already have.)
• Flying
• First strike
• Vigilance
• Lifelink
{W}: Until end of turn, if Embodied Soul isn't a creature, it becomes a 0/0 Spirit Avatar enchantment creature with “This creature gets +1/+1 for each different kind of counter on it.”

You may play an additional land this turn.
Draw a card.

Lifelink
When Stalked Healer enters the battlefield, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

[+2]: Create a 2/2 red Werewolf creature token with first strike and haste.
[–3]: Tanya deals 3 damage to each creature that's not a Wolf or a Werewolf.
[–8]: For each permanent your opponents control, that player sacrifices it unless they have Tanya deal 2 damage to them.

[+1]: Tanya, the Mooncursed becomes a legendary 3/1 red Werewolf creature with first strike until end of turn.
[–2]: Tanya, the Mooncursed deals 3 damage to target creature or planeswalker.
[–4]: Destroy target nonbasic colorless permanent.

Flash
When Veilborn Meddler enters the battlefield, counter target spell if its mana value is less than or equal to Veilborn Meddler's power.
Whenever you cast a spell during an opponent's turn, put a +1/+1 counter on Veilborn Meddler.

Riot (This creature enters the battlefield with your choice of a +1/+1 counter or haste.)
Whenever Wild Lifescale attacks, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Whenever Yri, the Daring Blade and exactly one other creature attack, Yri and that creature can't be blocked by creatures with mana value 3 or less this turn.