msem-instigator

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

Flying, trample
Once each turn, when you cast a spell from anywhere other than your hand, you may copy it. If you do, you may choose new targets for the copy.

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.

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.

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

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.)

Whenever an artifact or enchantment you control enters, Armament Scavenger gets +1/+0 and gains trample until end of turn.

As long as Armed Vendor is enchanted or equipped, it gets +1/+0 and has menace.

Prowess
When Arms Tinkerer enters, choose one —
• Destroy target artifact.
• Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Haste
Whenever Arpechian Tiger attacks, you may sacrifice a land. If you do, Arpechian Tiger deals 3 damage to target creature or planeswalker.

Double strike
Renown 2 (When this creature deals combat damage to a player, if it isn't renowned, put two +1/+1 counters on it and it becomes renowned.)

Arsenal Curator gets +1/+1 as long as you control a Plains.
{2}{W}: Untap target creature you control. It gets +0/+1 until end of turn.

When Artillery Mage enters, it deals 5 damage to target creature you don't control.
{5}{R}, {T}, Discard a card: Artillery Mage deals 5 damage to target creature you don't control.

Whenever you cast a noncreature spell, creatures you control get +1/+0 until end of turn.

Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, Artisan of Brutality gets +2/+0 and gains first strike until end of turn.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — You may sacrifice a permanent. When you do, As the Lanterns Float On deals 3 damage to any target.
II — You may sacrifice a permanent. When you do, exile the top two cards of your library. You may play them this turn.
III — Create a token that's a copy of target permanent card in your graveyard with mana value 4 or less. It gains haste. Sacrifice it at the beginning of the next end step.

Menace (This creature can't be blocked except by two or more creatures.)
Whenever Ash Breather deals combat damage to a player, you may discard a card. If you do, draw a card.

Ash Freebooter has first strike as long as it's attacking.
When Ash Freebooter enters, you may discard a card. If you do, draw a card.

Whenever you cast an Inscription spell, you may choose target creature you control. If you do, as that Inscription resolves, exile it inscribed onto that creature instead of putting it anywhere else.

Equipped creature gets +2/+2.
Art of war — At the beginning of your end step, if equipped creature dealt damage to an opponent this turn, target nonbasic land an opponent controls doesn't untap during its controller's next untap step.
Equip {2}

First mate — Twelve or more cards in your starting deck are Dragons or have “Dragon” in their printed rules text. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Dragon spells you cast cost {1} less to cast.
Whenever Ashe attacks, it deals X damage to any target, where X is the number of Dragons you control.