msem-instigator

Arcane Sanctum enters the battlefield tapped.
{T}: Add {W}, {U}, or {B}.

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.

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

Flying, vigilance

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

Flying
{1}: Archon of Supremacy gets +1/-1 until end of turn.

Flying, menace

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

({T}: Add {W} or {B}.)
Whenever Arctic Mine becomes tapped, you lose 1 life unless you control two or more basic lands.

Arid Causeway enters the battlefield tapped unless you control another Desert.
{T}: Add {R} or {W}.

[+1]: Tap up to one target creature. It doesn't untap during its controller's next untap step.
[–2]: Exile target card from a graveyard. Create a 2/2 blue and black Elemental creature token.
[–7]: You get an emblem with “You may play cards from exile.”

Whenever Arisen Helix attacks, scry 2.
If Arisen Helix would die, exile it instead.

Haste
Whenever Arisen Hunter attacks, target player loses 2 life and you gain 2 life.
If Arisen Hunter would die, exile it instead.

Whenever Arisen Rider attacks, creatures your opponents control get -1/-1 until end of turn.
If Arisen Rider or another creature or planeswalker would die, exile it instead.

Trample
Whenever Arisen Tyrant attacks, mill three cards, then you may exile a card from your graveyard. You may cast a copy of the exiled card without paying its mana cost if the spell's mana value is 3 or less.
If Arisen Tyrant would die, exile it instead.

Aristocrat's Gallery enters tapped.
When Aristocrat's Gallery enters the battlefield, look at the top card of your library. You may put it into your graveyard.
{T}: Add {G} or {U}.

At the beginning of your end step, you may put a progress counter on Armored Transports.
[PROGRESS 1-2] Creatures you control get +0/+1.
[PROGRESS 3+] Creatures you control get +0/+1 and have vigilance.

When Arpechian Groundskeeper enters the battlefield, rouse 1. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)
Remove a +1/+1 counter from Arpechian Groundskeeper: Draw a card.

{T}: Add {C}.
Harmony — Add one mana of any color.
{1}, {T}: Harmonize. (Trigger up to one harmony of one permanent you control.)

At the beginning of each upkeep, if an opponent controls more creatures than you, create a 1/1 colorless Thopter artifact creature token with flying.

When Artificial Wayfinder enters the battlefield, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

{T}: Draw a card. Artisan's Fountain doesn't untap during its controller's next untap step.

{T}: Add {C}{C}.
{2}: Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)