msem-instigator

Attacking creatures get -2/-0 until end of turn.
Metamorph {1}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

Destroy target artifact or enchantment. Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)

Target creature gets -X/-X until end of turn, where X is the number of enchantments you control.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
Spells you cast from zones other than your hand cost {3} less to cast.

Ominous Lair enters tapped unless you have 15 or less life.
{T}: Add {W} or {B}.

Exile target creature you control, then return that card to the battlefield under its owner's control. 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.”)

For each player, choose a creature or planeswalker that player controls. Each player sacrifices all creatures and planeswalkers they control not chosen this way.
Fuse (You may cast one or both halves of this card from your hand.)

Enchant creature
Whenever enchanted creature deals combat damage to a player, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

At the beginning of your upkeep, reveal the bottom card of your library. You may cast it if it's a creature card. Otherwise, exile it.

Ophan Titan gets +3/+3 as long as there are no nonland cards in your graveyard.
Morph {1}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

{T}: Add {G}. If you control an attacking creature, add one mana of any color instead.

Bleed {1}{B/R} (You may cast this spell for its bleed cost if an opponent has lost life this turn.)
Haste
When Opportunistic Raiders enters, if it's your main phase, after this phase, there is an additional combat phase followed by an additional main phase.

Creatures can't attack you unless their controller pays {3} for each of those creatures.

Scry 1.
Draw a card.

When Oracle of Edicts enters, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
Whenever an Aura you control enters, scry 1.

Whenever you cast a spell during an opponent's turn, put a +1/+1 counter on Oracle of Tides.

Whenever you sacrifice an Idol, put a +1/+1 counter on Orchard Botanist.

Identity — When Order's Anointer enters, if you control at least two other creatures that share a creature type with it, creatures you control get +1/+1 until end of turn.

Whenever Ore Tunneler deals damage to an opponent, tap target land they control. It doesn't untap during its controller's next untap step.

Whenever Organ Scavenger perseveres, each opponent loses 2 life. (A creature perseveres when it survives damage.)

Destroy target artifact or enchantment with mana value 3 or less.
Ferocious — You gain 4 life if you control a creature with power 4 or greater.

Flash (You may cast this spell any time you could cast an instant.)
Flying
When Orichi of the Cold Mist enters, exile another target creature you control. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Ornamented Evergreen enters tapped unless you have two or more opponents.
{T}: Add {G} or {W}.

You may cast spells as though they had flash.

Flying
Whenever an opponent casts a spell, counter it unless that player pays {1} for each spell cast before it this turn.