Kifimbo, Shadow Guildmage

When Kifimbo enters the battlefield, add
{b}{b}{b}{b} to your mana pool.
When Kifimbo is put back into the command zone from anywhere, add {b}{b} to your mana pool.
Pact (You can have two commanders if both have pact. If the two commanders share a creature type, they cost {x} less to cast, where X is number of times the commander's been cast.)