Arcane Signet

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

Command Tower

Island

Sol Ring

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

The Scarab God

At the beginning of your upkeep, each opponent loses X life and you scry X, where X is the number of Zombies you control.
{2}{U}{B}: Exile target creature card from a graveyard. Create a token that's a copy of it, except it's a 4/4 black Zombie.
When The Scarab God dies, return it to its owner's hand at the beginning of the next end step.

Jet Medallion

Black spells you cast cost {1} less to cast.