msem-instigator

Vigilance, trample
Whenever another Horror enters the battlefield under your control, choose one —
• Destroy target artifact or enchantment.
• You gain 4 life.
• Apex Abomination fights another target creature.

At the beginning of your upkeep, if an opponent controls more creatures than you, you may reveal the top seven cards of your library. Target opponent chooses a creature card revealed this way. Put that card onto the battlefield, and the rest into your graveyard.

Target creature you control deals damage equal to its power to target creature or planeswalker you don't control.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “III—You may cast a copy of this card from exile without paying its mana cost.”)

Whenever Apprehensive ‘Slinger deals combat damage to a player or planeswalker, you may discard a card. If you do, draw a card.

When Apprentice Summoner enters the battlefield, search your library for a creature card with mana value 1 or less, put it onto the battlefield, then shuffle.

When Appropriated Gear enters the battlefield, create a Treasure token.
Equipped creature gets +1/+1.
Equip {2}

Other creatures you control can't attack or block alone.

{1}{R}: Aravant Throatcutter and up to one other target Pirate or Rogue you control each get +1/+0 until end of turn.

Target creature you control deals damage equal to its power to target creature you don't control.

This spell costs {1} less to cast for each differently named land you control.
Reach, trample

As long as Arboreal Runes is on the battlefield or in your graveyard, it's a Forest land in addition to its other types.
{T}: Add one mana of any color.

Activated abilities of artifacts cost {2} more to activate.

Whenever Arcane Metalcrafter or another Wizard you control attacks, create a 1/1 colorless Construct artifact creature token that's tapped and attacking.
Whenever a Construct you control dies, Arcane Metalcrafter deals 1 damage to each opponent.

Harmony — Attach Arcane Saxophone to target creature.
When Arcane Saxophone enters the battlefield, harmonize. (Trigger up to one harmony of one permanent you control.)
Equipped creature gets +2/+2.
Equip {4}

{T}: Add one mana of any color in your commander's color identity.

Wanderlust — When you cast this spell, you may copy it if you control four or more differently named lands.
Exile the top two cards of your library. Until the end of your next turn, you may play those cards. Create a colorless land token named Fading Rift with “{T}, Sacrifice this land: Add one mana of any color.”

Gain control of target artifact or creature until end of turn. Untap it. It gains haste until end of turn.

Whenever you cast a noncreature spell, Architect of Calamity deals 2 damage to each opponent.

Target opponent chooses a number. When they do, choose one —
• That player discards their hand, then draws cards equal to the chosen number.
• Archivist's Torment deals damage to that player equal to the chosen number.

Whenever Archlegislator attacks, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
{3}{R}{R}, {T}, Sacrifice an Aura: Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn.

You have no maximum hand size.
{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Flying
Whenever Archon of Inspiration attacks, add three mana in any combination of colors at the beginning of your next postcombat main phase.

Flying, trample

{T}: Add {C}.
{2}, {T}, Sacrifice Arcor Diamond: Draw a card.

Create three 2/2 green Wolf creature tokens.