Defending Bone + Goblin Skull Bomb

[Isaac Zephyr]

I'm always the type to think of odd combos.

RAW for these two things, Defending Bone (Inner Sea Gods), and the Goblin Skull Bomb (Ultimate Equipment), Defending Bone needs a medium creature's skull (or femur, but for this instance we're considering a skull) as one of the focuses. Goblins are small, though their heads are massive by comparison to most small creatures. Ignoring that, creatures killed with the Goblin Skull Bomb leave behind their skull, so kill a medium humanoid with it and that problem is solved.

Obviously due to it's hardness and HP, the skull bomb would not be able to sponge 5 × caster level HP from bludgeoning attacks. It might give you DR 5/bludgeoning for the first attack, or even only DR 1 against the attack, but the important part is by the Skull Bomb's effect, even touching it through a tool activates it, so the attack would destroy it and immolate the attacker for 5d6 fire. Exception being sling or thrown hammer, ranged bludgeoning attacks, which if the bomb was activated, would immolate the caster. The same risk with the bomb as normal.

The two questions that would arise:

1: Would the Goblin Skull Bomb be able to be used as the focus for the spell? It is a skull, and could be from a medium creature, but does it being a magic item make it invalid for the focus.

2: Would Defending Bone negate the Goblin Skull Bomb? That being, in using the Goblin Skull Bomb as the focus, would Defending Bone's magic come first? Turning it into a regular skull to sponge 5 × caster level HP. I guess that's a priority question of what is taken to consideration first, spell or magic item effect?

Optional Question 3: If the spell ended without an attack hitting the bomb, would it break? The spell's time is in hours, so it's unlikely to happen during a combat, but if it was ended prematurely or dispelled. It floats around you so being dispelled it would drop, and break by it's own rules, immolating the caster (or last person who touched it, could supposedly have a familiar or ally hold it if you felt like being a jerk. Hell, if you were transporting the skull bomb with Mage Hand and\or a Bag of Holding so that it wasn't pre-activated and therefore only the attacker would be the option). Ending the effect of the spell though, could you not prevent it falling by holding it at the end, with your own hands or Mage Hand persay (which by the skull bomb's description doesn't activate it).

[Darkblitz9]

This seems like a house rule sort of thing, but my take on it would be this:

It's too small to use initially for Defending Bone, as it's a goblin's skull, even though Goblins have big noggins, the skull needs to come from a medium creature.

Not a big deal, make sure to use it to kill a medium creature, and then use that skull.

It fits the requirements for Defending bone at that point, and I'd say that the skull would provide no DR against the attack (simply dropping it causes it to shatter, it's very fragile), but would definitely blow up whoever's trying to hit you.

If the spell effect ends via time limit, I'd say that the caster could get away with carefully catching it as a reflex save (with a bonus if they dismiss it).

Definitely not an interaction that's outright intended, but it doesn't seem unreasonable to assume it could be used in such a way.

So for your questions:

1. Yes, but only once it's a skull from a medium creature, the initial item created via craft wondrous would be that of a Goblin skull (small creature) and wouldn't work initially.

2. I don't think so, I think the point of defending bone is using something hard to take the blows, but the Goblin Skull Bomb is fragile by description. It wouldn't stop you from levitating the bone in order to block attacks, and transfer the blast to a would-be attacker, but I don't think it would provide any DR.

3. If it hits the ground, definitely. I'd allow a reflex safe to catch it when the duration runs out, as well as granting a bonus granted if you dismiss the spell, and a penalty if the spell was dispelled by something else (such as dispell magic)