msem-instigator

Abyss Howler must be blocked if able.
Whenever Abyss Howler becomes blocked, defending player loses 2 life and you gain 2 life.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Abyssal Accuser must be blocked if able.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
When Abyssal Familiar dies, it deals 1 damage to you and to any target.

When Abyssal Pact enters the battlefield, you draw two cards and each player loses 2 life.
Players can't gain life.
Damage can't be prevented.

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

You have no maximum hand size.
{T}: Add {C}.
{3}, {T}: Create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

{T}: Add {C}.
{T}, Sacrifice Alchemist's Abode and another permanent: Draw a card. Activate only during your turn.

Flying, vigilance

Activated abilities of sources you don't control can't be activated unless they're mana abilities.

Until end of turn, target creature loses all abilities and becomes a colorless Human with base power and toughness 1/1 and no name.

Flash
Enchant creature
When Arcane Anesthesia enters the battlefield, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Counter target instant or sorcery spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

When Artillery Mage enters the battlefield, it deals 5 damage to target creature you don't control.
{5}{R}, {T}, Discard a card: Artillery Mage deals 5 damage to target creature you don't control.

Whenever you cast a noncreature spell, creatures you control get +1/+0 until end of turn.

Ash Freebooter has first strike as long as it's attacking.
When Ash Freebooter enters the battlefield, you may discard a card. If you do, draw a card.

{T}: Draw two cards. Starting with the next opponent in turn order, each opponent may discard a land card. The first to do so gains control of Ashen Mare. Activate only during your turn.

Prevent all combat damage that would be dealt this turn.
Create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

Whenever you play a land, return a card at random from your graveyard to your hand.
Whenever you cast a green spell, reveal the top card of your library. If it's a land card, put it into your hand. Otherwise, mill it.

Autumn Ward's power and toughness are each equal to the number of creature cards in your graveyard.
Unveil {2}{B}{G} ({2}{B}{G}: Transform this. Unveil only as a sorcery.)

Flying
Harmony — Until the end of your next turn, you may cast target instant or sorcery card from your graveyard. If that card would be put into your graveyard, exile it instead.
When Aven Acoustimancer enters the battlefield, harmonize. (Trigger up to one harmony of one permanent you control.)

Your opponents can't cast spells or activate abilities that aren't mana abilities this turn.

Whenever Barker Duelist becomes blocked, defending player loses 1 life.
Unveil {3}{B}{R} ({3}{B}{R}: Transform this. Unveil only as a sorcery.)

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Whenever Barrow Banshee deals combat damage to an opponent, that player discards a card at random.

Whenever Beatrice's Dodger attacks, create a 1/1 black and red Human Rogue creature token that's tapped and attacking.
{3}{B}{R}: Return Beatrice's Dodger from your graveyard to the battlefield
tapped and transformed.

Draw a card, then reveal any number of creature or land cards from your hand. You gain that much life.