Galvitar

[Wildhorn]

Does the Forcemaster has to declare if the attack will be with Doublestrike OR Sweeping before the first attack or she can decide on the go as needed?

[Enti]

Page 22 in the english rulebook says:

Step 1. Declare Attack
Announce which attack you are using.

You could argue, that this only applies if you have 2 or more attackbars to choose from. But in my opinion the intention of the whole step is, to tell your oponent exactly what you are going to do. So my interpretation would be, that you have to tell him in advance, if you use doublestrike or sweeping.

[Zuberi]

"OR" Attacks
Some attacks have an “OR” in their attack bar, which gives you a choice of traits or abilities to use with that attack. When the attack is declared, the controller decides which of these alternatives will apply for the attack.

You have to select which trait during the Declare Attack Step.

[Shad0w]

Page 22 in the english rulebook says:

Step 1. Declare Attack
Announce which attack you are using.

You could argue, that this only applies if you have 2 or more attackbars to choose from. But in my opinion the intention of the whole step is, to tell your oponent exactly what you are going to do. So my interpretation would be, that you have to tell him in advance, if you use doublestrike or sweeping.

Even with one attack bar the selection still happens even if the choice is "locked".