Essence Harvest

Target player loses X life and you gain X life, where X is the greatest power among creatures you control.

Dark Favor

Enchant creature
When Dark Favor enters, you lose 1 life.
Enchanted creature gets +3/+1.

Hero's Downfall

Evernight Shade

{B}: Evernight Shade gets +1/+1 until end of turn.
Undying (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.)

Escaped Null

Lifelink
Whenever Escaped Null blocks or becomes blocked, it gets +5/+0 until end of turn.

Endless Obedience

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Put target creature card from a graveyard onto the battlefield under your control.

Homicidal Seclusion

As long as you control exactly one creature, that creature gets +3/+1 and has lifelink.

Increasing Ambition

Search your library for a card and put that card into your hand. If this spell was cast from a graveyard, instead search your library for two cards and put those cards into your hand. Then shuffle.
Flashback {7}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Necrobite

Target creature gains deathtouch until end of turn. Regenerate it. (The next time that creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Squelching Leeches

Squelching Leeches's power and toughness are each equal to the number of Swamps you control.

Aspect of Gorgon

Enchant creature
Enchanted creature gets +1/+3 and has deathtouch. (Any amount of damage it deals to a creature is enough to destroy it.)

Bloodcrazed Hoplite

Heroic — Whenever you cast a spell that targets Bloodcrazed Hoplite, put a +1/+1 counter on it.
Whenever a +1/+1 counter is put on Bloodcrazed Hoplite, remove a +1/+1 counter from target creature an opponent controls.

Agent of the Fates

Deathtouch
Heroic — Whenever you cast a spell that targets Agent of the Fates, each opponent sacrifices a creature of their choice.

Swamp

Bone Splinters

As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature.