While the current level of equipment destruction is OK in my opinion, it should be readjusted regarding the harshness, i.e. how it is calculated.

"your heap of 10 scrolls of corruption removal is dissolved!" and no other items are hit.

I suggest you make it so that it hits more items at a time but for one certain item it won't destroy more than, say, 25 % of all the ones you have. The current way adds too much randomness to the destruction, as with enough bad luck, one dragon can ruin the game pretty badly. With more diverse destruction, you would still need to consider twice before attacking a greater dragon vault or roaming the BDC, since the destruction would be inevitable in the long run anyway.