msem-instigator

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

Flying, trample

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

Flying, menace

({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 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, look at the top card of your library. You may put it into your graveyard.
{T}: Add {G} or {U}.

Target creature you control gets +2/+2 until end of turn. If it's attacking, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

Target creature gains double strike until end of turn.

Trample
Arpechian Champion can only attack or block alone.
Whenever a land you control enters, put a +1/+1 counter on Arpechian Champion.

Enchant land
When Arrive, Surrounded by Petals enters, audition for green. (Create a 1/1 Construct Actor creature token, a Scout Role giving 2/3 and vigilance, or a Warrior Role giving 3/2 and trample. Roles replace older ones.)
Enchanted land has “{T}: Add one mana of any color.”

Target creature gets +1/+1 until end of turn. Untap that creature.
Fabled {2}{W} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that creature.)

Winnow (Damage dealt to this creature also causes you to lose that much life.)
{2}{B}: Each creature blocking Arroyo's Servant gains winnow until end of turn.

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

Flying
Improve {1}{U} ({1}{U}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)

{T}: Add one mana of any color. Each other player adds one mana of any color at the beginning of their next first main phase.

Hexproof
At the beginning of your upkeep, put a card from your hand on top of your library. You may shuffle.
{1}: Look at the top three cards of your library, then put them back in any order.
{2}{U}: Draw a card.

{T}: Add {C}.
{5}, {T}, Sacrifice Ascendant's Cell: You may activate loyalty abilities of planeswalkers you control twice this turn rather than only once.

{T}: Add {C}.
{T}: Add one mana of any color. Activate only if you control a transformed permanent.

The next time target creature would be dealt damage this turn, prevent all but 1 of that damage. Whenever that creature perseveres this turn, put a +1/+1 counter on it. (A creature perseveres when it survives damage.)