Damping Sphere vs Hall of Gemstone

[Fjaulnir]

New card leaked:

Damping Sphere
2
Artifact
If a land is tapped for two or more mana, it produces C instead of any other type and amount.
Each spell a player casts costs 1 more to cast for each other spell that player has cast this turn.


How does this interact with [card]Hall of gemstone[/card]?

Does Hall become a replacement effect after it has triggered? In that case I'd think I can choose whether I want my Serra's Sanctum to tap for say 6 green or for 1 colorless right?
But if it's not a replacement effect Sphere would win...

[H]

Hmm, I am not a judge, but since both seem to be replacement effects, you can choose the order, but the thing is, it won't matter if Sactum is tapping 2 or more mana.

Let us pretend Sanctum taps for X, where X is greater than 1 and lets assume we pick Green for Hall (it doesn't really matter).

Applying Hall's effect first, turns X White mana into X Green mana. The applying Sphere turns that into One Colorless.

If we apply Sphere first, we get One Colorless mana, which is not actually effected by Hall.

So, either way, Sphere would win, I believe.

[Fjaulnir]