Harm or Heal spell when targeting a friendly undead unit

[Forkedwizard]

I was wondering which of these spells would I use to heal (restore HP) my undead party memeber? The rules seem confusing since they both seem to refer to eachother when dealing with an undead unit.

Heal:
If used against an undead creature, heal instead acts like harm.

Harm:
If used on an undead creature, harm acts like heal.

My intuition is that the intent of the spell caster would determine which one I should use. (Heal since I'm trying to heal them)

[Firebug]

Since Heal can get rid of conditions and Harm can't take the target below 1 hp, I think they just wanted to note that they have the opposite effect on undead but that the damage type (positive vs negative) doesn't change.

IE, you use Heal on an undead creature (regardless of intent) it takes positive energy damage equal to what Harm would have done instead. So 10/CL but with the minimum of 1 hp. It wouldn't cure conditions and then damage them. If you used Harm on an undead, it would cure conditions and heal HP like Heal would, though it stays negative energy.

[blahpers]

Intent is not relevant.

If you use heal on an undead creature, it will damage them as though you had cast harm on a living creature. If you use harm on an undead creature, it will heal them as though you had cast heal on a living creature (including curing conditions and so on).

[thorin001]

Blaphers has it right. This is a positive/negative interaction, not one of intent.

[MrCharisma]

Heal is a Positive Energy spell, like Cure Light Wounds. Positive energy spells restore HP to living creatures and deal damage to undead creatures.

Harm is a Negative energy spell, like Inflict Light Wounds. Negative Energy spells deal damage to living creatures and restore HP to undead creatures.

[SheepishEidolon]

This reversed behaviour has surprising consequences when you as a GM put harm traps on doors and the group starts using the dhampir wizard to neutralize them...

And previous posters made an interesting point: Harm heals some conditions undead creatures could suffer from. Becomes more relevant when Thanatopic Spell was used, since it makes undead vulnerable to death effects, negative levels and energy drain.