msem-instigator

Whenever Bourasan Street Watch attacks, you may pay {W}. If you do, Bourasan Street Watch gains indestructible until end of turn.

{T}: Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
At the beginning of combat on your turn, you may exile a creature card from your graveyard. When you do, target creature with the same power as the exiled card can't be blocked this turn.

Enchant creature
Enchanted creature can't attack or block unless its controller pays {3}.
Activated abilities of enchanted creature cost {3} more to activate.

At the beginning of your end step, draw two cards and you lose 2 life.

This spell costs {1} less to cast for each creature and/or planeswalker card in your graveyard.
Return target creature or planeswalker card from your graveyard to the battlefield.

Shock deals 2 damage to any target.

Flying
When Andazir Assaulter enters, recruit. (Create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)

Hexproof
{1}{W}{U}, {T}: Exile target creature you control. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Slums Thug gets +1/+1 and has menace as long as you've gained life this turn.

Trial 4 (As you cast this spell, an opponent of your choice may pay 4 life. If they don't, they fail the trial.)
You draw two cards and you lose 2 life. Target player discards two cards if they failed the trial.

{T}: Add {R}.
{R}, {T}: Target creature gains haste until end of turn.

Each artifact you control has all the activated abilities of other artifacts you control.

Rhapsody {4}{U}{U} (Pay {4}{U}{U} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
When Unstable Prophet enters, surveil X, where X is its power. (Look at the top X cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Flash
Flying
When Justiciar Overseer enters, the next 2 damage that a source of your choice would deal to you and/or permanents you control this turn is dealt to any target instead.

Put target tapped creature and all other creatures with the same name as that creature on the bottom of their owners' libraries.

For each creature token you control, create a token that's a copy of that creature.

Hollowghast, the Iron Phantom enters with three +1/+1 counters on it.
If damage would be dealt to Hollowghast, prevent that damage. Remove a +1/+1 counter from Hollowghast.

Lifelink
Whenever you sacrifice a nonland permanent, you may pay {1}. If you do, you draw a card and you lose 1 life.

When Somnambulance enters, each player conjures a card named Fatigue and puts it on top of their library. (It's a colorless sorcery that costs {2} with “Draw a card.”)
Whenever a player casts a spell named Fatigue, you may draw a card. If you do, you lose 1 life.

Destroy target artifact.
Reprise {R} (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.)

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Mighty Xioshu can't be blocked by creatures with power 2 or less as long as you're in a renaissance.

Wary Rider has first strike as long as its attacking.
Wary Rider gets +1/+0 as long as you control two or more other creatures.

{2}{G}, {T}: Another target creature you control gets +2/+2 until end of turn.

When Symbiotic Sprout dies, create two 1/1 green Saproling creature tokens.

Exotic Vista enters tapped.
{T}: Add {G} or {U}.
When Exotic Vista enters, you may put a loyalty counter on a planeswalker you control.