msem-instigator

Target creature you control deals damage equal to its power to target creature or planeswalker you don't control.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Whenever Apprehensive ‘Slinger deals combat damage to a player or planeswalker, you may discard a card. If you do, draw a card.

When Apprentice Summoner enters, search your library for a creature card with mana value 1 or less, put it onto the battlefield, then shuffle.

At the beginning of your end step, put an encroachment counter on Approach of Old Lovi, then it deals X damage to any target and you gain X life, where X is the number of encroachment counters on Approach of Old Lovi.

As Approach the Dark Tomb enters, choose life or death.
• Life — Whenever you cast a creature spell, you may pay 1 life. If you do, draw a card.
• Death — Whenever a creature you control dies, you may pay 1 life. If you do, draw a card.

Enchant artifact or creature
At the beginning of each upkeep, if enchanted permanent is tapped, untap it.
You control enchanted permanent.

When Appropriated Gear enters, create a Treasure token.
Equipped creature gets +1/+1.
Equip {2}

Counter target spell. Draw a card, then discard a card.

Target creature gets +2/+2 until end of turn. If it's an enchanted creature or enchantment creature, it also gains hexproof and indestructible until end of turn. (It can't be the target of spells or abilities your opponents control. Damage and effects that say “destroy” don't destroy it.)

As Aquatic Refuge enters, you may tap an untapped creature you control. If you don't, Aquatic Refuge enters tapped.
{T}: Add {W} or {U}.

{U}: Aqueous Treader gets +1/-1 until end of turn.
{U}: Aqueous Treader gets -1/+1 until end of turn.

Other creatures you control can't attack or block alone.

At the beginning of your upkeep, you may pay {1}{G/U}. If you do, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)
At the beginning of your end step, you may pay {1}{G/U}. If you do, populate. (Create a token that's a copy of a creature token you control.)

Flying, lifelink
Improve {1}{W/B} ({1}{W/B}: 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.)
Once each turn, when you gain life, you may have each opponent lose 2 life.

Whenever you foretell a card or cast a foretold spell, each opponent loses 1 life and you gain 1 life.

Whenever Aravant Smuggler deals combat damage to an opponent, if it's embattled, draw a card. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

{1}{R}: Aravant Throatcutter and up to one other target Pirate or Rogue you control each get +1/+0 until end of turn.

Equipped creature gets +2/+2.
Whenever equipped creature deals combat damage to a player, exile cards from the top of their library until they exile a nonland card. You may cast that card without paying its mana cost.
Equip {2}

Target creature you control deals damage equal to its power to target creature you don't control.

Vigilance
If another creature would die, exile it instead.
At the beginning of your upkeep, return each creature card exiled with Arbiter of Endless Summer to the battlefield under its owner's control.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
When Arbiter of Shal'Iv enters, adjudicate. (Create a white enchantment Aura token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)

Flying
When Arbiter of Silence enters, exile all other creatures until Arbiter of Silence leaves the battlefield. (They return to the battlefield under their owners' control.)

{2}{B}, Sacrifice a creature: Draw a card. You gain 1 life.

Flash
Flying
As long as an opponent controls more creatures than you, Arbiter of the Scales gets +2/+2 and has first strike and lifelink.

This spell costs {1} less to cast for each differently named land you control.
Reach, trample