Once you've unlocked the Aspect of Achilles for the Eternal Spear, you'll gain the Raging Rush ability. This gives you an extra 50%+ bonus damage for the next 4 attacks. To keep track of its effects, pay attention to the fire effects on Zagreus. While Raging Rush is active, you'll have animated flames on your body. Use this as an advantage to reactivate Raging Rush as soon as it wears off.