Magus of the Coffers + Sword of the Paruns

Magus of the Coffers
Sword of the Paruns

Requires
Magus of the Coffers must be on the battlefield. Sword of the Paruns must be on the battlefield. Magus of the Coffers is not summoning sick and can tap for mana. At least six Swamps under your control. 4 to start the combo (or 2 and Sword of the Paruns attached to Magus of the Coffers).
Steps
  1. Pay 2 to activate Magus of the Coffers, adding at least six b (including initial mana, floating 8).
  2. Pay 3 to attach Sword of the Paruns to Magus of the Coffers (floating 5).
  3. Activate Sword of the Paruns, untapping Magus of the Coffers (floating 2).
  4. Repeatedly tap the Magus for mana and untap it, generating at least b per iteration.
Results
Infinite black mana.