Smoldering Marsh

({T}: Add {B} or {R}.)
Smoldering Marsh enters tapped unless you control two or more basic lands.

Arcane Signet

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

Rowan, Scion of War

Menace
{T}: Spells you cast this turn that are black and/or red cost {X} less to cast, where X is the amount of life you lost this turn. Activate only as a sorcery.

Rakdos Signet

Terminate

Destroy target creature. It can't be regenerated.

Moltensteel Dragon

({R/P} can be paid with either {R} or 2 life.)
Flying
{R/P}: Moltensteel Dragon gets +1/+0 until end of turn.

Command Tower

Talisman of Indulgence

{T}: Add {C}.
{T}: Add {B} or {R}. Talisman of Indulgence deals 1 damage to you.

Wall of Blood

Defender (This creature can't attack.)
Pay 1 life: Wall of Blood gets +1/+1 until end of turn.

Vorrac Battlehorns

Equipped creature has trample and can't be blocked by more than one creature.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Greven, Predator Captain

Menace
Greven, Predator Captain gets +X/+0, where X is the amount of life you've lost this turn.
Whenever Greven attacks, you may sacrifice another creature. If you do, you draw cards equal to that creature's power and you lose life equal to that creature's toughness.