How does bonus damage from the 'Intense Spells' class ability relate to the 'Fire Shield' spell?

Question

Evocation Wizards in Pathfinder benefit from bonus damage to their offensive spells, but I am wondering how this relates to spells like Fire Shield.

Intense Spells (Su): Whenever you cast an evocation spell that deals hit point damage, add 1/2 your wizard level to the damage (minimum +1). This bonus only applies once to a spell, not once per missile or ray, and cannot be split between multiple missiles or rays. This bonus damage is not increased by Empower Spell or similar effects. This damage is of the same type as the spell. At 20th level, whenever you cast an evocation spell you can roll twice to penetrate a creature's spell resistance and take the better result.

Fire Shield: Any creature striking you with its body or a handheld weapon deals normal damage, but at the same time the attacker takes 1d6 points of damage + 1 point per caster level (maximum +15). This damage is either cold damage (if you choose a chill shield) or fire damage (if you choose a warm shield). If the attacker has spell resistance, it applies to this effect. Creatures wielding melee weapons with reach are not subject to this damage if they attack you.

Technically Fire Shield is an Evocation spell that deals hit point damage (albeit in an indirect way), but I’m not sure how to interpret the bonus damage rules in relation to this sort of spell. How does 'Intense Spell' increase the damage of 'Fire shield'?

Answer 1

Aether's answer certainly has good point, but I think you can argue his interpretation both ways (Fire Shield is an evocation spell that needs to be cast at some point and certainly can deal hitpoint damage, after all) since the ability doesn't explicitly mention that the spell needs to deal damage at the time of casting (this interpretation would also rule out some signature evocation spells like Delayed Blast Fireball from getting any benefits from this abiltiy).

I'd personally follow this line in the ability's description:

[...] This bonus only applies once to a spell, not once per missile or ray, and cannot be split between multiple missiles or rays. [...]

and allow the extra damage to be dealt once per casting of the spell (e.g. on the first hit, or on a single hit the caster decides). This would allow the character to still benefit from the class ability when using the spell but prevent it from being cheesed.

Answer 2

It's somewhat ambiguous, so there's a case to be made for allowing it to add the damage based on the wording, but from my understanding of those rules as written, Fire Shield doesn't deal hit point damage on casting, so you don't get to add 1/2 your wizard level to the damage (since it says you add the damage "whenever you cast an evocation spell").

As unsatisfying as it may be, this may come down to GM ruling.

If the damage does apply, it only applies to the first damage done by the shield, though.