msem-instigator

Anran's Realm enters the battlefield tapped.
{T}: Add {R} or {G}.
{R}{G}, {T}: Create a Function token with “This spell can't be countered.” Activate only if you control a creature with power 4 or greater. (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Flash
Flying
At the beginning of each end step, if two or more spells were cast this turn, you may draw a card. If you do, discard a card.

Equipped creature gets +1/+0 and has “{T}: This creature deals 1 damage to target player or planeswalker.”
Equip {2}

Each land is an Island in addition to its other land types.

You may look at an additional card each time you scry.
{2}, Tap two untapped creatures you control: Scry 1.

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

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

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

Arcane Oasis enters the battlefield tapped unless you control another Desert.
{T}: Add {U} or {R}.

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

Equipped creature gets +1/+0.
Whenever equipped creature attacks, you may draw a card then discard a card.
Equip {2}

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

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

({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 the battlefield tapped unless you control another Desert.
{T}: Add {R} or {W}.

Whenever Arisen Helix attacks, scry 2.
If Arisen Helix would die, exile it instead.

Aristocrat's Gallery enters tapped.
When Aristocrat's Gallery enters the battlefield, 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 enters the battlefield under your control, put a +1/+1 counter on Arpechian Champion.

Enchant land
When Arrive, Surrounded by Petals enters the battlefield, 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.