Sacrifice

As an additional cost to cast this spell, sacrifice a creature.
Add an amount of {B} equal to the sacrificed creature's mana value.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Doomed Necromancer

{B}, {T}, Sacrifice this creature: Return target creature card from your graveyard to the battlefield.

Henzie "Toolbox" Torre

Each creature spell you cast with mana value 4 or greater has blitz. The blitz cost is equal to its mana cost. (You may choose to cast that spell for its blitz cost. If you do, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)
Blitz costs you pay cost {1} less for each time you've cast your commander from the command zone this game.

Hell's Caretaker

{T}, Sacrifice a creature: Return target creature card from your graveyard to the battlefield. Activate only during your upkeep.

Stalking Vengeance

Haste
Whenever another creature you control dies, it deals damage equal to its power to target player or planeswalker.

Greenwarden of Murasa

When this creature enters, you may return target card from your graveyard to your hand.
When this creature dies, you may exile it. If you do, return target card from your graveyard to your hand.

Pelakka Wurm

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
When this creature enters, you gain 7 life.
When this creature dies, draw a card.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Thragtusk

When this creature enters, you gain 5 life.
When this creature leaves the battlefield, create a 3/3 green Beast creature token.

Life's Legacy

As an additional cost to cast this spell, sacrifice a creature.
Draw cards equal to the sacrificed creature's power.

Food Chain

Exile a creature you control: Add X mana of any one color, where X is 1 plus the exiled creature's mana value. Spend this mana only to cast creature spells.

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.

Birds of Paradise

Nissa of Shadowed Boughs

Landfall — Whenever a land you control enters, put a loyalty counter on Nissa.
+1: Untap target land you control. You may have it become a 3/3 Elemental creature with haste and menace until end of turn. It's still a land.
−5: You may put a creature card with mana value less than or equal to the number of lands you control onto the battlefield from your hand or graveyard with two +1/+1 counters on it.

Ignoble Hierarch

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
{T}: Add {B}, {R}, or {G}.

Culling the Weak

As an additional cost to cast this spell, sacrifice a creature.
Add {B}{B}{B}{B}.

Weatherlight Compleated

Flying
As long as Weatherlight Compleated has four or more phyresis counters on it, it's a Phyrexian creature in addition to its other types.
Whenever a creature you control dies, put a phyresis counter on Weatherlight Compleated. Then draw a card if it has seven or more phyresis counters on it. If it doesn't, scry 1.

Liliana, Dreadhorde General

Whenever a creature you control dies, draw a card.
+1: Create a 2/2 black Zombie creature token.
−4: Each player sacrifices two creatures of their choice.
−9: Each opponent chooses a permanent they control of each permanent type and sacrifices the rest.