msem-instigator

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.

Counter target spell. If a permanent spell is countered this way, create a Gold token. (It's an artifact with “Sacrifice this artifact: Add one mana of any color.”)

Whenever Arcane Duelist becomes tapped, target instant or sorcery card with mana value 1 in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)

{U}, Exile an instant or sorcery card from your graveyard: Draw a card, then discard a card.
{R}, Exile an instant or sorcery card from your graveyard: Arcane Harvesters deals 1 damage to any target.

Search your library for an instant or sorcery card, reveal it, put it into your hand, then shuffle.

Counter target spell.
Look at the top three cards of your library. Put one on top and the rest on the bottom in any order.

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

Harmony — Attach Arcane Saxophone to target creature.
When Arcane Saxophone enters, 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.

Whenever you cast a spell, draw a card if that spell has the same name as a card in your graveyard.

Counter target spell unless its controller pays {2}.
Reprise {3}{U} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)

Until end of turn, creatures you control get +1/+1 and gain prowess. If there are two or more instant and/or sorcery cards in your graveyard, draw a card.

When Arcanomancer enters, return up to one target instant card and up to one target sorcery card from your graveyard to your hand.

Wanderlust — When you cast this spell, you may copy it if you control four or more differently named lands.
Exile the top card of your library. Until the end of your next turn, you may play that card. Create a 1/1 Scout creature token that's all colors.

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.

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

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

Create three 2/2 green Wolf creature tokens.

[+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

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.)

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.

Menace, haste
As long as Arleigh, Spellblade Prodigy is tapped, the first spell you cast during each other player's turn costs {U/R} less to cast. This effect reduces only the amount of colored mana you pay. (For example, if you cast a spell with mana cost {1}{R}, it costs {1} to cast.)

Flying
Whenever a creature you control phases in, it gains flying until end of turn.