Does Overwhelming Energy work against resist all?

Question

Overwhelming Energy:

[...] the spell ignores an amount of the target’s resistance to acid, cold, electricity, fire, or sonic damage equal to your level

A Wraith for example has resist all 5.

If I am on level 10 and cast Fireball (rolling 35) after activating Overwhelming Energy, how much damage does the Wraith take:

1. Its resistance against the fire damage is lowered by 5, taking full damage
2. Resist all is not a collection of all resistances, but a different quality, which is not lowered, so the Wraith takes 30 damage
3. Other

Answer 1

I think it is safe to assume that "resist all" is only a shortcut for having all the separate resistances. (so apply case 1: Its resistance against the fire damage is lowered by 5, taking full damage)

Unfortunately the rulebook is not very precise about this, the only thing about "resist all" is:

It’s possible to have resistance to all damage. When an effect deals damage of multiple types and you have resistance to all damage, apply the resistance to each type of damage separately. If an attack would deal 7 slashing damage and 4 fire damage, resistance 5 to all damage would reduce the slashing damage to 2 and negate the fire damage entirely.

which doesn't help to answer your question.

However, from playing the game, I can tell that having fire resistance of a foe not being reduced while you invested class features for that is not fun. Let the players use their cool stuff !