Crescendo in arcane slot, any rank is fine.
If no Crescendo, alternatives include Melee Exposure or Melee Retaliation

Attack Speed is capped at 55% and berserker fury works.
Spoiled Strike + Berserker Fury = 75% - 20% = 55%.

Note that the bonus given by elemental mods like [Primed Fever Strike] and Melee Exposure are affected by armor (i.e. reduced by 10 at max armor), but will deal the full damage against unarmored enemies and the overguard component of enemies. [Primed Fever Strike] is therefore flexible for [Primed Smite Grineer] if specifically fighting only armored Grineer.