Dargo, the Shipwrecker

To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases (such as the commander tax), then apply any cost reductions (such as that of Dargo's first ability). Dargo's mana value is 7, no matter what the total cost to cast it was.

Once the game begins, your two commanders are tracked separately. If you cast one, you won't have to pay an additional {2} the first time you cast the other. A player loses the game after having been dealt 21 damage from any one of them, not from both of them combined.

Dargo's first ability can't reduce its cost below {R}. You can sacrifice any number of artifacts and creatures, even if they won't reduce Dargo's cost any further.

The cost reduction is {2} per sacrificed permanent, whether that permanent was an artifact, a creature, or both.

To have two commanders, both must have the partner ability as the game begins. Losing the ability during the game doesn't cause either to cease to be your commander.

If something refers to your commander while you have two commanders, it refers to one of them of your choice. If you are instructed to perform an action on your commander (e.g. put it from the command zone into your hand due to Command Beacon), you choose one of your commanders at the time the effect happens.

If your Commander deck has two commanders, you can only include cards whose own color identities are also found in your commanders' combined color identities. If Falthis and Kediss are your commanders, your deck may contain cards with black and/or red in their color identity, but not cards with green, white, or blue.