What Rage activates

Rage is the decision point for Frenzy and the condition that powers Mindless Rage. The subclass becomes much harder to charm or frighten while raging, and a Frenzied Rage trades future exhaustion for extra attacks during the fight.

What remains useful outside Rage

Intimidating Presence and Retaliation are not both locked behind Rage in the 2014 feature text, so the Berserker still has subclass tools when Rage is unavailable. The core offensive identity, however, is strongest during Rage.

The normal Rage restrictions still matter

Frenzy intensifies Rage rather than replacing its normal rules. A Berserker still cannot cast or concentrate on spells while raging under the 2014 rules, so multiclass spellcasting competes directly with the subclass's main offensive mode.

Why Rage duration matters

Ending a Frenzied Rage is especially important because that is when the exhaustion cost is applied. The player should therefore think about the entire adventuring day, not only the current round, when deciding whether to Frenzy.