Ability scores

Dexterity remains the main ability. Constitution helps survival. Wisdom can fit a spirit-sensitive investigator, but the subclass's major combat features do not require a separate spellcasting ability.

Weapons and Sneak Attack

A normal finesse or ranged weapon remains the trigger for Sneak Attack and therefore for Wails from the Grave. Because Wails needs a successful Sneak Attack first, accuracy and target access are more important than chasing a separate attack routine.

Action economy

Treat Wails from the Grave as a way to spread pressure when two important enemies are present. Preserve reactions when a Soul Trinket opportunity matters. Outside combat, Whispers of the Dead lets you adapt to the next task after a rest without permanently committing every proficiency choice.

Skills and Expertise

Whispers of the Dead gives the Phantom a changing proficiency after rests, so permanent Expertise can focus on core Rogue jobs such as Stealth, Perception, or thieves' tools while the borrowed proficiency covers situational needs.

Common mistake

A common mistake is treating Wails from the Grave as a second Sneak Attack. It is a separate subclass effect triggered after Sneak Attack damage is dealt. That distinction matters for critical hits, damage modifiers, and rules that specifically reference Sneak Attack.