Clarification on GURPS Magic: Explode?

[Calvin]

This is about Explode, as it appears on page 118 of the GURPS Magic .pdf

My GM and I have rather different interpretations on how damaging it is, and what it can do. We have since reached an agreement on how to handle it, but I'm holding out hope that Kromm or someone else who matters will see this and give us the "official" ruling on the matter. Otherwise I'd like to see how other groups handle the spell.

I'll do my best to represent both of our interpretations, and I'm sure my GM will yell at me if I get his wrong.

My interpretation:
Damage in is damage out. Basically if you put in the full 12 energy for 3d6+6 damage (Assuming this is enough to destroy the item) you get 3d6+6 in damage per fragment. I argue that the damage scales the same as missile spells, and in exchange for a greater damage to the people outside of the inital hex you get greater risk, and must stand quite a bit closer due to it being a Regular spell.

And I think it does this regardless of the mass of the object. I argue that the increased damage is represented by increased energy imparted on the fragments, and that the ease at which smaller items are destroyed (and so allows you to get the frag effect with less risk) is balanced by the fact that such small items are probably less important than something larger. (Like a sword, or piece of armor)

The GM's interpretation:
Fragmentation damage is a minor secondary effect compared to the destruction of the item. Rather than do the 1d6/2FP damage I assume, instead the damage destroys the thing (Assuming it's enough), and then the damage dealt is based on the Incidental Fragmentation rules. So 1d6 damage rather than the same damage that was dealt to the item. For the GM the utility of being able to destroy an item accounts for the FP cost and relative balance of the spell when compared to others. He also thought that being able to do 3d6+6 damage by Exploding a coin was unreasonable. I kinda concede that point to him, but for me the coin's irrelevance combat wise and the fact that I'm more concerned with relative damage output meant that I was less concerned with silly things like "logic"


Our compromise:
1. Frag damage is capped at the HP of the item destroyed, plus 25%. If it was just capped at HP then I'd probably not use the spell. The chances of either putting too little energy in and getting nothing, or spending too much and wasting energy, meant that I'd rather just use Explosive Fireball. The +25% allows for some leeway there.
2. Energy input is capped at Magery*2, just like with Explosive missile spells. The vanilla 2-6 seems to sort of line up with this already, assuming a M3 caster, though it allows for lower Magery casters to have a chance of destroying bigger things. But then my guy is Magery 4, so a higher cap is nice when trying to make sure there is a decent probability of something actually breaking.

[Lancewholelot]

Originally Posted by Calvin

The GM's interpretation:
Fragmentation damage is a minor secondary effect compared to the destruction of the item. Rather than do the 1d6/2FP damage I assume, instead the damage destroys the thing (Assuming it's enough), and then the damage dealt is based on the Incidental Fragmentation rules. So 1d6 damage rather than the same damage that was dealt to the item. For the GM the utility of being able to destroy an item accounts for the FP cost and relative balance of the spell when compared to others. He also thought that being able to do 3d6+6 damage by Exploding a coin was unreasonable. I kinda concede that point to him, but for me the coin's irrelevance combat wise and the fact that I'm more concerned with relative damage output meant that I was less concerned with silly things like "logic"

After reading the spell, I believe your GM has interpreted the effect correctly.

[Anthony]

It's actually fairly overpowered to allow the full damage as fragments, so I would use the GMs rule. Let's look at a sample case:

I cast Explode on his helmet
Lessee, a pot-helmet is a 5 lb object, homogenous, for 14 hit points. Explode is like Shatter is like Weaken, which means the helmet's DR doesn't protect. The spell is not resisted, and regular spells cannot be dodged, parried, or blocked. As the subject is in contact with the helmet, he is automatically hit; hit location for contact explosions is not covered in the rules but is presumably the same as the location covered by the armor, which is skull. So, for 12 fatigue I do 3d+6, which has about a 75% chance to explode the helmet, and will cause 3d6+6 to the skull, which is no longer protected by armor, so the victim takes an average of 16.5 damage vs DR 2, with x4 after DR, for an average of 58 hit points...

In addition, his unlucky companions are hit by fragments. They are 2 yards away. They are not subject to the contact rule, and instead are attacked with skill 15, with one additional hit per 3 MOS, for an average of about 2.5 hits, each hit doing 3d+6 cutting. If they have DR 6, the average injury is around 40 points.

By comparison, a 12 fatigue explosive fireball would do 7 points of damage at 2 yards.

[Calvin]

Well, when you sell it like that it's hard to justify my interpretation.

For actual use though the distance penalties really mess with the caster. My character for example knows the spell at 17. Let's say I want to go to skill 11 (62.5% chance). That's 6 yards, +2 for my staff. 8 Yards.

This is the part where I remembered that frag damage max range is dice*5 yards.

Okay, you've totally successfully convinced me. It may not be my most efficient way of taking out enemies, but it's actually useful without being OP.

[Culture20]

Originally Posted by Anthony

I cast Explode on his helmet

On a great-helm's faceplate or a TL 4-5 wizard's spectacles would attack the eyes... >:-)