Sanguine Syphoner

Whenever this creature attacks, each opponent loses 1 life and you gain 1 life.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Training Center

Training Center enters tapped unless you have two or more opponents.
{T}: Add {U} or {R}.

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Command Tower

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

Stormfist Crusader

Menace
At the beginning of your upkeep, each player draws a card and loses 1 life.

Howling Mine

At the beginning of each player's draw step, if Howling Mine is untapped, that player draws an additional card.

Have

Nekusar, the Mindrazer

At the beginning of each player's draw step, that player draws an additional card.
Whenever an opponent draws a card, Nekusar, the Mindrazer deals 1 damage to that player.

Arcane Signet

Gloomlake Verge

{T}: Add {U}.
{T}: Add {B}. Activate only if you control an Island or a Swamp.

Counterspell

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.