In another thread, http://privateerpressforums.com/show...93#post1482093 , it was discovered that the frenzy activation interrupt Dr. Arkadius's activation when his feat is used.
Dr. Arkadius has five warbeasts, A through E.
Dr. Arkadius activates and then uses his feat. Warbeasts A, B, and C are nominated to frenzy. Arkadius's player then chooses one of those warbeasts to activate, resolves the frenzy; chooses again and resolves again; and then resolves the remaining frenzy. Then Arkadius's activation continues.
Dr. Arkadius activates and then uses his feat. Arkadius's player chooses a warbeast, it frenzies, and the frenzy is resolved. Arkadius's activation then continues, and resolution of the feat continues. If Arkadius's player wishes, another beast is chosen, and that beast frenzies, again interrupting Dr. Arkadius. When Arkadius's activation resumes, Arkadius's player decides that this is enough, and ends the resolution of the feat.
Scenario #2 seems nicer since it avoids stacking up any pending activations, but the whole situation is a bit unusual.