Commander

[Taysby]

My commander is nekusar. I have out {alter of dementia} and {rooftop storm}.  Can I play my commander for free infinite times, sacking him to the alter for infinite mill?  Or do I have to pay the extra cost to play him?

[Sardok]

You have to pay the additonal cost of {2} per subsequent time your general is cast from the command zone.

[DylanW18]

Read the first ruling of the card

"You must pay any additional, mandatory costs"

[Kaleo42]

Let me start by saying there is no official rules for commander and my following statements are not backed up or affiliated to me being a level 1 judge.

My understanding of commander costs is that it is an additional cost to cast. A cost increase if you will. {Heartless summoning} will reduce this increase when applied allowing your second cast of {zur the enchanter} to be the same cost as your first. By this understanding {rooftop storm} would also apply completely making the final cost zero regardless of casts. Do keep track though incase you lose the storm before the game ends.

Order for casting:
Declare
Name mode
Name targets
Determine cost increases
Determine cost decreases
Determine cost modifiers ({trinisphere}, {rooftop storm}, {omniscience})
Pay the cost

[Kaleo42]

Read the first ruling of the card

"You must pay any additional, mandatory costs"

The example it gives is not mana related. This is referring to cards like {skaab ruinator}.

[DylanW18]

Read the first ruling of the card

"You must pay any additional, mandatory costs"

The example it gives is not mana related. This is referring to cards like {skaab ruinator}.

My bad..

[Sardok]

117.9d If an alternative cost is being paid to cast a spell, any additional costs, cost increases, and cost reductions that affect that spell are applied to that alternative cost. (See rule 601.2e.)

903.10. A player may cast a commander he or she owns from the command zone. Doing so costs that player an additional {2} for each previous time he or she cast that commander from the command zone that game.

Together, these two rules mean you still have to pay the additional {2} per cast.

[particle]

bump.