msem-instigator

Thriving Bluff enters tapped.
As Thriving Bluff enters, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Opera House enters tapped.
When Opera House enters, add one mana of any color.
{T}, Sacrifice Opera House: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

{T}: Add {C}.
{4}, {T}, Put a -1/-1 counter on a creature you control: Draw a card.

{T}: Add {C}.
{T}, Sacrifice Alchemist's Abode and another permanent: Draw a card. Activate only during your turn.

When Witch's Invitation enters, you may put a -1/-1 counter on target creature.
{2}, {T}: Tap target creature with a -1/-1 counter on it.

Creatures blocking or blocked by Straw Officer have wither. (They deal damage to creatures in the form of -1/-1 counters.)

As Publishing Press enters, you may exile a nonland card with mana value 2 or less from your hand.
At the beginning of your upkeep, you may cast a copy of the exiled card without paying its mana cost if the spell's mana value is 2 or less.

{2}, {T}, Sacrifice Pale Morningstar Powder: Put two -1/-1 counters on target creature.

When Mechanical Mastodon enters, you may return another target permanent you control to its owner's hand.

When Imperfect Stone enters, mill three cards.
{T}: Add one mana of any color.

Equipped creature gets +1/+0 and has wither. (It deals damage to creatures in the form of -1/-1 counters.)
Equip {2}

{3}, {T}: Glimmering Staff deals 1 damage to any target.
{5}, {T}: Put a -1/-1 counter on target creature.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

You have no maximum hand size.
{T}: Add {C}.
{3}, {T}: Create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

Wither (This deals damage to creatures in the form of -1/-1 counters.)
When you unveil Bramble Quickling, you may have it fight target creature.

Flash
Unveil {3}{B}{G} ({3}{B}{G}: Transform this. Unveil only as a sorcery.)

{T}: Add one mana of any color.
Whenever you tap Ingrained Virago for mana, each opponent loses 1 life.

{T}, Pay 1 life: Add {C}.
Unveil {3}{B}{G} ({3}{B}{G}: Transform this. Unveil only as a sorcery.)

Vigilance, deathtouch, menace

Deathtouch
Unveil {3}{B}{G} ({3}{B}{G}: Transform this. Unveil only as a sorcery.)

[+2]: Put a -1/-1 counter on or remove a -1/-1 counter from up to one target creature.
[–1]: Draw a card, then each player sacrifices a nonland permanent.
[–10]: Destroy all nonland permanents you don't control.

{T}: Exile two target creature and/or land cards from a graveyard. Create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
{B}{G}, Sacrifice two Vials: Sacrifice Leticia Petrine, then return her to the battlefield transformed under her owner's control.

Mill three cards, then you may return a creature or land card from your graveyard to your hand.

When Gallipot Apothecary enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

As an additional cost to cast this spell, sacrifice a creature.
Draw cards equal to the sacrificed creature's power.