billd91
Not your screen monkey (he/him)
From the additional rules:
Energy Attacks: Energy attacks deal half damage to most objects. Divide the damage by 2 before applying the object's hardness. Some energy types might be particularly effective against certain objects, subject to GM discretion. For example, fire might do full damage against parchment, cloth, and other objects that burn easily. Sonic might do full damage against glass and crystal objects.
So you'll need to deal at least 42 points of damage with an energy attack to have it inflict damage (other than fire, to which that particular monster is immune), but for a party of that level, that shouldn't be impossible.
I would recommend not halving the damage done by energy before applying the hardness. That applies to objects, sure, but animated objects have a creature type of construct. They're not your typical objects. They're hit points are calculated differently as are their saves and a variety of other topics. They should take damage more like a creature than a standard object.
My players have been working their way through the campaign with a gnome witch, a halfling rogue, a halfling ranger (specialized in staff sling attacks), and a dwarf monk. The rogue had a magic adamantine dagger, the ranger a few adamantine bullets (he always buys a mix for just such occasions), and the witch bought a wand of lightning bolts at 10th level casting power. I recall the cage being a bit more of a challenge than the fiend it holds, but only a little bit.
They had much more trouble with Zovarue, in fact.