msem-instigator

Whenever you cast a black spell, choose up to X, where X is the number of black mana symbols in that spell's mana cost —
• Target player loses 1 life and you gain 1 life.
• Put a -1/-1 counter on target creature.
• You draw a card and you lose 3 life.
• Exile target card in a graveyard.

Each instant and sorcery card in your hand has cycling {2}. ({2}, Discard this card: Draw a card.)
At the beginning of your end step, if there are four or more instant and/or sorcery cards in your graveyard, you may pay {1}{U/R}. If you do, return an instant or sorcery card at random from your graveyard to your hand.

Your opponents play with the top card of their library revealed.
Your opponents can't cast spells during your turn.
You may play lands and cast spells from the top of an opponent's library during your turn.

When Ornery Bull enters, return a creature you control to its owner's hand.

Whenever Orphan Prodigy is dealt damage, it deals that much damage to target player.
Attain {4}{R} ({4}{R}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Vigilance
You may look at the top card of your library any time.
Whenever you cast a creature spell from your hand, you may cast the top card of your library without paying its mana cost if it's a creature card with lesser mana value.

Whenever Orria Mirrorpelt becomes the target of a spell, exile that spell. If Orria Mirrorpelt was its only target, copy it for each other creature target player controls. Each copy targets a different one of those creatures.

Pressure {3}{B} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
When Oryxyth's Brood enters, you draw two cards and you lose 2 life.

Whenever you make first contact, Oscuran Wingmate gains flying until end of turn. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Lifelink
At the beginning of your upkeep, Osgaerith Desecrator deals 1 damage to up to one target creature.

All creatures able to block Osheen Courtier do so.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

When Osseous Augur enters, target creature an opponent controls gets -1/-1 until end of turn. If that creature's controller is cursed, that creature gets -3/-3 until end of turn instead.

Whenever you cast a noncreature spell, up to one target artifact or non-Aura enchantment you control becomes a 3/3 creature in addition to its other types until end of turn.

Out-of-Depth Amateur can't attack or block alone.
Attain {4}{R} ({4}{R}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Outfitted Ibex has menace as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Outlands Bodyguard can't attack alone.
You may exert Outlands Bodyguard as it attacks. When you do, it must be blocked this turn if able. (An exerted creature won't untap during your next untap step.)

{G}, Tap an untapped Nymph you control: Overgrown Beast gets +2/+2 until end of turn.

Whenever Overgrowth Host attacks, germinate. Then creatures you control that are Saprolings or have counters on them gain trample until end of turn.
Saprolings you control get +1/+1.

This spell can't be countered.
Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Haste (This creature can attack and {T} as soon as it comes under your control.)

Flash
Flying
When P05 Suppressor enters, create a Function token with “Tap target creature. Put a stun counter on it.” (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
Whenever you cast another spell with flash or an instant, put a stun counter on up to one target creature if it's tapped. Otherwise, tap it.

Lifelink
Whenever Painstriker attacks, it deals 2 damage to target creature defending player controls.

{2/W}, {T}: Tap target creature.

First strike
Civilized — Whenever Palace Enforcer attacks, if you control an artifact, a creature, and an enchantment, Palace Enforcer gains deathtouch and lifelink until end of turn.

{2}{W}{B}: Exile up to two cards from a single graveyard. Recruit. Activate only as a sorcery. (Create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)