msem-instigator

First strike
Whenever a player loses life, creatures you control get +1/+0 until end of turn.

Choose a number. Reveal that many cards from the top of your library and put them into your hand. You lose life equal to the total mana value of those cards.

Flying
Herald of Oblivion enters the battlefield with X -1/-1 counters on it, where X is your life total.

{T}: Add {C}.
{3}: Mill two cards, then return Midnight Keep from your graveyard to the battlefield tapped.

Whenever you attack, you may double target attacking creature's power. If you do, sacrifice it at the beginning of the next step.
Whenever one or more red creatures enter the battlefield under your control, creatures you control get +1/+0 and gain trample until end of turn.

Look at the top two cards of your library. Put one of them into your hand and the rest into your graveyard.
Rerun (If you cast this from your hand, exile it as it resolves. Whenever a creature you control dies, you may cast this card from exile without paying its mana cost.)

Deathtouch
Putrid Lurker can't block.
Whenever you discard Putrid Lurker or another card, you may pay {B}. If you do, return Putrid Lurker from your graveyard to the battlefield.

This spell costs {2} less to cast for each Horror you control.
Exile up to one target non-Horror creature.
Coalesce {8}{W} (You may cast this from your graveyard for its coalesce cost. If you do, put it onto the battlefield as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield with an additional -1/-1 counter on it. If you search your library this way, shuffle.

Whenever Watch Me Burn enters the battlefield or another source you control deals noncombat damage, put an ignition counter on Watch Me Burn. Then it deals damage equal to the number of ignition counters on it to each opponent.