Charge Outburst is the action window
Hatred covers its face and curls into a floating ball. The potion warning appears, and the charge ends its whole turn. Use Ghost Potion on your response action before Outburst; ordinary blocking and superguarding cannot stop the blast.
The potion costs 1 SP and leaves you Exhausted afterward. Heal before the charge window when needed, and do not spend your last SP on an attack while waiting for the warning.
Mechanics references: Hatred · Ghost Potion
Prayer works only at the HP threshold
Above 10 HP, Hatred absorbs Prayer and it has no effect. At 10 HP or less, Prayer deals 1,000 damage to the enemies. Read the current HP before selecting it. Its normal action costs 5 SP, so reaching the threshold with no SP is not enough.
Guard the ordinary attacks separately
PK Thunder gasps twice before the overhead lightning strike for 12 piercing damage. Corruption sends three separated orbs for 4 each and can Confuse. Maintain three distinct inputs for the orbs instead of stopping after the first hit.
A practical resource check
Before a charged window, the immediate reserve is 1 SP for Ghost Potion. If you also intend to use Prayer afterward, those two actions need 6 SP in total unless you restore SP between them. They do not happen on the same action, and Exhausted can delay the finisher. This arithmetic does not predict whether your build can survive the intervening turn.
Unlock and rematch
The first clear ends the Chapter 3 Dream World arc and leads to Ghostwalker. That sword cannot be part of your first Hatred clear. Afterward, answer Nothing to Guru to enter the rematch.