msem-instigator

Put target creature on top of its owner's library.
Quickdraw {2}{U} (When a creature you control blocks or becomes blocked, you may cast this spell for {2}{U}.)

When Healing Center enters, you gain 2 life.
{T}: Add {C}.

Menace
When Heart of the Deadwood enters, destroy up to one target creature, then put up to one target creature card from a graveyard onto the battlefield under your control.

Gain control of target attacking creature until end of turn. Untap it. It gains indestructible until end of turn.

At the beginning of your upkeep, if you have less life than an opponent, you lose 1 life and you draw a card.

Reach

Enchant creature
Prevent all damage that would be dealt by enchanted creature.
{R}, Sacrifice Heat of Day: It deals 2 damage to enchanted creature.

Until end of turn, gain control of target creature and it gains haste and shimmer. Untap it. (Whenever it attacks this turn, create a tapped and attacking token that's a copy of it. Exile that token at the beginning of the end step.)

{1}, {T}: Add one mana of any color.
{1}, {T}, Sacrifice Heavy Moneybag: Post a bounty on target creature or planeswalker. Activate only as a sorcery. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)

[+1]: Tap target nonland permanent. It doesn't untap during its controller's next untap step.
[–2]: Exile target tapped nonland permanent.
[–4]: Target player skips their next untap step. Tap up to three target permanents.

{T}, Pay 1 life: Add {U} or {R}.
{1}, {T}, Sacrifice Heist Headquarters: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Menace
{1}{B}{R}: Creatures you control get +1/+0 until end of turn.

{6}: Until the next time this ability resolves, and as long as Helm of the Infinite and target creature you control are on the battlefield, each other creature is a copy of that creature, and effects that would cause permanents to become creatures cause them to become copies of that creature instead.

Whenever you lose 2 or more life during your turn, put two blood counters on Hemomancy.
{1}{B}, Remove X blood counters from Hemomancy: Return target creature card with mana value X from your graveyard to the battlefield.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Put a +1/+1 counter on target creature you control. It gains vigilance until end of turn.
III — Target creature you control gets +2/+2 and gains flying, vigilance, and lifelink until end of turn.

Whenever another nontoken creature you control dies, create a 1/1 green Saproling creature token.
{B}{G}, {T}, Sacrifice a creature: Return target permanent card from your graveyard to your hand.

When Here Forever enters, exile target creature or planeswalker until Here Forever leaves the battlefield.
At the beginning of your upkeep, the owner of the exiled card loses 1 life.

Target opponent may draw two cards. If they do, you draw four cards. Otherwise, you create four 1/1 red Elemental creature tokens.

Heretic's Home enters tapped.
{T}: Add {R} or {G}.
When Heretic's Home enters, you may put a loyalty counter on a planeswalker you control.

{1}{U}, {T}: Reveal the top card of your library. If it doesn't share a color with Heretical Seer, put it into your hand.

For each color among nontoken permanents you control, add one mana of that color.

When Hex Maniac enters, return target non-Human creature card from your graveyard to your hand.

{T}, Pay 1 life: Add {G} or {U}.
{1}, {T}, Sacrifice Hidden Hollow: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Flash
When Hidden Sprout enters, put a +1/+1 counter on target creature.

Target creature gains flying and gets +1/+0 for each card in your hand until end of turn.
Fuse (You may cast one or both halves of this card from your hand.)