msem-instigator

When Debaser of Truth enters the battlefield, if you control three or more Horrors, each opponent discards two cards.
Other Horror creatures you control get +1/+1.

Decay deals damage to creatures in the form of -1/-1 counters.
{B}{G}: Until end of turn, target creature deals damage to creatures in the form of -1/-1 counters. Activate only if Decay is in your graveyard.

Flash
When Decisive Arcanist enters the battlefield, you may cast target modal instant or sorcery card in your graveyard. Exile that card instead of putting it into your graveyard as it resolves.

Haste
{R}, Sacrifice Deepstone Operative: Destroy target artifact.

Whenever you cast a spell, if it shared a color with the last spell you cast this turn, put two +1/+1 counters on Defected Android.

Whenever Defective Abomination attacks, you may sacrifice a permanent. If you do, put a +1/+1 counter on it. It gains indestructible until end of turn.

Deft Goldsnatch can't be blocked.

Flash
When Dehmi, Origin Seeker enters the battlefield, counter target spell an opponent controls unless that spell's controller has you create X 1/1 red Elemental creature tokens, where X is that spell's mana value.

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Each creature you control with a counter on it has ward {2}. (If a creature has multiple instances of ward, each triggers separately.)

Delusional Noble enters the battlefield with a -1/-1 counter on it.

Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)
When Demolitionist Deviser dies, it deals damage equal to its power to any target.

At the beginning of your end step, if you've sacrificed three or more permanents this turn, return Demon of Necessary Evil from your graveyard to the battlefield.

First strike
Whenever Deprived Div deals combat damage to an opponent, end the turn. (Creatures without first strike won't deal damage this turn.)

Flash

{B}, Sacrifice another creature: Deranged Apothecary gains indestructible until end of turn.

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
{2}, Sacrifice a creature: Put a +1/+1 counter on Desert Marauder.

Desert Slaughterer can't block.
{B}, Remove a +1/+1 counter from a creature you control: Return Desert Slaughterer from your graveyard to the battlefield with a +1/+1 counter on it.

Menace
Whenever Despair Scavenger attacks, you may have target creature get -1/-1 until end of turn.

Desperate Android enters the battlefield tapped.
Whenever another artifact you control dies for the first time each turn, return Desperate Android from your graveyard to your hand.

{1}, Sacrifice a creature: Desperate Forsaken gets +1/+1 until end of turn. You gain 1 life.

Sacrifice a land: Desperate Ravager gets +2/+0 and gains haste until end of turn.

Haste
Whenever Desperate Reconnoiterer becomes untapped, scry 1.

Assault {1}{B} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
Whenever a creature you control assaults, you may have target creature get -2/-2 until end of turn.

Menace
{1}{B}, Exile another three cards from your graveyard: Return Determined Explorer from your graveyard to your hand.

Whenever Determined Hero attacks, upgrade it. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)