Felnar said:
is it satisfying to have any old adamantine weapon perform better than a Mattock of the Titans?
It certainly isn't satisfying, and I foresee the problems if this becomes a regular tactic (but, here they know the layout of the cave, which makes it a much more useful idea). I see few reasonable solutions that don't have cascading impacts. Make a judgment call here, and it has effects that reverberate through the campaign.
The "weapon not suited to task" judgment call works fine, up until the dwarf gets a pick.
The "weapon risks being damaged" house-rule is taking away adamantine's most important properties -- it's REALLY GOOD at destroying objects and really hard to damage. And it doesn't match the mechanics for fighting stone golems or animated objects.
The "wielder becomes fatigued" house-rule falls short if it doesn't apply to combat (watch how quickly boxers get tired).
The "require Profession checks or cause cave-in" judgment call would be appropriate in some places but not in here (due to the geometry and the shortness of the tunnel). The cascading impact here is where do you draw the line. A thoqqua's 1-ft diameter hole probably has no chance of causing a cave-in. A delver's 10-ft hole, more likely.
The "can't Power Attack inanimate objects" house-rule results in the odd situation where the evil adamantine idol becomes much easier to destroy if you cast Animated Objects on it. But, with moboesen's in-game explanation, it's the best fix I've seen. It makes damaging objects a much more difficult process.
Looks like rules for damaging objects, like the time for crafting items or the AC for attacking held/worn items, have some serious unintended consequences.