Final Punishment

Target player loses life equal to the damage already dealt to that player this turn.

Assault Suit

Equipped creature gets +2/+2, has haste, can't attack you or planeswalkers you control, and can't be sacrificed.
At the beginning of each opponent's upkeep, you may have that player gain control of equipped creature until end of turn. If you do, untap it.
Equip {3}

Devour in Shadow

Destroy target creature. It can't be regenerated. You lose life equal to that creature's toughness.

Belt of Giant Strength

Equipped creature has base power and toughness 10/10.
Equip {10}. This ability costs {X} less to activate, where X is the power of the creature it targets.

Blackblade Reforged

Equipped creature gets +1/+1 for each land you control.
Equip legendary creature {3}
Equip {7}

Raised by Giants

Commander creatures you own have base power and toughness 10/10 and are Giants in addition to their other types.

Flay Essence

Exile target creature or planeswalker. You gain life equal to the number of counters on it.

Graveblade Marauder

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Whenever Graveblade Marauder deals combat damage to a player, that player loses life equal to the number of creature cards in your graveyard.

Archfiend of Despair

Flying
Your opponents can't gain life.
At the beginning of each end step, each opponent loses life equal to the life that player lost this turn. (Damage causes loss of life.)

Wound Reflection

At the beginning of each end step, each opponent loses life equal to the life they lost this turn. (Damage causes loss of life.)

Sarevok, Deathbringer

At the beginning of each player's end step, if no permanents left the battlefield this turn, that player loses X life, where X is Sarevok's power.
Choose a Background (You can have a Background as a second commander.)

Blitzwing, Adaptive Assailant

Living metal (During your turn, this Vehicle is also a creature.)
At the beginning of combat on your turn, choose flying or indestructible at random. Blitzwing gains that ability until end of turn.
Whenever Blitzwing deals combat damage to a player, convert it.

Blitzwing, Cruel Tormentor

More Than Meets the Eye {3}{B} (You may cast this card converted for {3}{B}.)
At the beginning of your end step, target opponent loses life equal to the life that player lost this turn. If no life is lost this way, convert Blitzwing.

Blitzwing, Cruel Tormentor // Blitzwing, Adaptive Assailant

Argentum Armor

Equipped creature gets +6/+6.
Whenever equipped creature attacks, destroy target permanent.
Equip {6}

Deadly Tempest

Destroy all creatures. Each player loses life equal to the number of creatures they controlled that were destroyed this way.

Devour Flesh

Target player sacrifices a creature of their choice, then gains life equal to that creature's toughness.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.