msem-instigator

Firehearth Halls enters tapped unless you control a basic Mountain.
{T}: Add {R}.
{R}{R}: Firehearth Halls becomes a 1/1 red Dwarf Warrior creature with double strike until end of turn. It's still a land.

Whenever you make first contact, you may tap target creature. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Destroy target artifact or land. If a land was destroyed this way, its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffle.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Whenever you cast a noncreature spell, any number of target creatures you control get +1/+1 until end of turn.
Whenever a creature you control deals an amount of combat damage exactly equal to its mana value to a player or planeswalker, draw a card.

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.

Whenever you draw a card, put a dream counter on Stargazing.
Remove seven dream counters from Stargazing and exile it: Shuffle your hand and graveyard into your library, then draw seven cards.

Tap target creature. Put a stun counter on it.
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)