How often and when can a multi-classed battle berserker frenzy?

Question

The Battle Berserker multiclass feat gives a daily use of the Berserker Fury class feature:

You also gain the berserker barbarian’s Berserker Fury feature, but you can use it only once per day.

The Berserker Fury feature reads:

When you use a barbarian primal attack power, you enter your Berserker Fury until the end of the encounter. Alternatively, you can use a minor action while you are bloodied to enter the fury. The fury has the following effects.

If a character has the Battle Berserker multiclass feat and uses Novice Power to pick up a primal, barbarian encounter attack power, how does this all play out?

a) Each encounter the character can frenzy by using the barbarian primal encounter attack power and once per day they could use a minor action while bloodied to trigger the frenzy.

b) The first time the character uses the barbarian primal encounter attack power they frenzy regardless of if they wanted to or not, and in subsequent encounters that day, they could not frenzy by any means.

c) Each time the character uses the barbarian primal encounter attack power they may frenzy if they have not already frenzied that day.

Or some other option?

Answer 1

As far as I can tell from the text of the class feature, combined with the feat text it looks as if interpretation b is the correct one. You must frenzy when you use the encounter power for the first time (alternatively you can turn the frenzy on with a minor). However you may not frenzy again for the rest of the day when this happens.

The spirit of the feat is to give you access to the Berserker's Fury class feature once per day and should not be able to be broken by simply taking an encounter power swap feat. (And I don't think the current wording allows for this kind of breakage)