Demon's Horn

Whenever a player casts a black spell, you may gain 1 life.

Ian the Reckless

Whenever Ian the Reckless attacks, if it's modified, you may have it deal damage equal to its power to you and any target. (Equipment, Auras you control, and counters are modifications.)

Arcane Signet

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

Batterskull

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +4/+4 and has vigilance and lifelink.
{3}: Return Batterskull to its owner's hand.
Equip {5}

Blazing Sunsteel

Equipped creature gets +1/+0 for each opponent you have.
Whenever equipped creature is dealt damage, it deals that much damage to any target.
Equip {4}

Loxodon Warhammer

Equipped creature gets +3/+0 and has trample and lifelink.
Equip {3}

Sol Ring

Arcbond

Choose target creature. Whenever that creature is dealt damage this turn, it deals that much damage to each other creature and each player.

Donna Noble

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
Whenever Donna or a creature it's paired with is dealt damage, Donna deals that much damage to target opponent.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Angel's Feather

Whenever a player casts a white spell, you may gain 1 life.

Expedited Inheritance

Whenever a creature is dealt damage, its controller may exile that many cards from the top of their library. They may play those cards until the end of their next turn.

Wurm's Tooth

Whenever a player casts a green spell, you may gain 1 life.

Witch's Clinic

{T}: Add {C}.
{2}, {T}: Target commander gains lifelink until end of turn.

Shadowspear

Equipped creature gets +1/+1 and has trample and lifelink.
{1}: Permanents your opponents control lose hexproof and indestructible until end of turn.
Equip {2}

Basilisk Collar

Equipped creature has deathtouch and lifelink. (Any amount of damage it deals to a creature is enough to destroy it. Damage dealt by this creature also causes you to gain that much life.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Hazoret's Monument

Red creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, you may discard a card. If you do, draw a card.

Paradise Plume

As Paradise Plume enters, choose a color.
Whenever a player casts a spell of the chosen color, you may gain 1 life.
{T}: Add one mana of the chosen color.

War Elemental

When War Elemental enters, sacrifice it unless an opponent was dealt damage this turn.
Whenever an opponent is dealt damage, put that many +1/+1 counters on War Elemental.

Coalhauler Swine

Whenever Coalhauler Swine is dealt damage, it deals that much damage to each player.

Dragon's Claw

Whenever a player casts a red spell, you may gain 1 life.

Staff of the Flame Magus

Whenever you cast a red spell or a Mountain you control enters, you gain 1 life.

Auntie Blyte, Bad Influence

Flying
Whenever a source you control deals damage to you, put that many +1/+1 counters on Auntie Blyte, Bad Influence.
{1}{R}, {T}, Remove X +1/+1 counters from Auntie Blyte: It deals X damage to any target.

Sun Droplet

Whenever you're dealt damage, put that many charge counters on Sun Droplet.
At the beginning of each upkeep, you may remove a charge counter from Sun Droplet. If you do, you gain 1 life.

Kraken's Eye

Whenever a player casts a blue spell, you may gain 1 life.

Feldon, Ronom Excavator

Haste
Feldon, Ronom Excavator can't block.
Whenever Feldon is dealt damage, exile that many cards from the top of your library. Choose one of them. Until the end of your next turn, you may play that card.