msem-instigator

When Archaeomancer enters, return target instant or sorcery card from your graveyard to your hand.

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

When Architect of the Derezzed enters, create two 1/1 colorless Servo artifact creature tokens.
Sacrifice an artifact: Target creature can't be blocked this turn.

Reach
When Archived Intelligence enters, surveil 2. Then if you control a token, draw a card.

When Archivist Heretic enters, you lose 1 life, then investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Flying, prowess

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 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.

Exile up to three target creatures you control, then return those cards to the battlefield under your control tapped.

When Arcor-Staff Adherent enters, you may remove all -1/-1 counters from target creature.

Create three 2/2 green Wolf creature tokens.

Attacking creatures you control get +1/+0 until end of turn.
Draw a card.

Wanderlust — When Ardent Explorers enters, if you control four or more differently named lands, create a 1/1 Scout creature token that's all colors. That token gains haste until end of turn.

Kicker {1}{R} (You may pay an additional {1}{R} as you cast this spell.)
Attacking creatures get +2/+0 until end of turn. Those creatures also gain first strike until end of turn if this spell was kicked.

[+1]: Search your library for a land card, put it onto the battlefield, untap it, then shuffle. Sacrifice a land.
[–2]: Destroy target noncreature permanent. Its controller may search their library for a basic land card, put that card onto the battlefield, then shuffle.
[–6]: Return any number of land cards from your graveyard to the battlefield and untap them. They become 3/3 creatures with haste in addition to their other types.

Whenever Arena Challenger deals damage to a creature, upgrade it. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• First strike
• Prowess

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

When Aridland Camaar enters, create a 1/1 white Bird creature token with flying.

If a creature would leave the battlefield this turn, exile it instead.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, target player sacrifices a creature.

When Arisen Haploc enters, return target creature card from a graveyard to its owner's hand.
Revive {5}{B}{B} ({5}{B}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)