Unorthodox Cave-in Clearing (3.5e Variant Rule)
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Unorthodox Cave-in Clearing
...in addition to traditional digging, there is a chance that an equally powerful concussion can remove a cave-in completely in a single round. Such an attempt is dangerous, however, because there is a chance (40%+(%=damage dealt)) that it could trigger a second cave-in or make the first deeper. In addition, clearing a cave-in by concussion will do 2d8 damage to any characters trapped by the rockfall.
Most concussion forces are not strong enough to remove a full-fledged cave-in. The best recommended tool for such an attempt is a satchel pack of dynamite- two sticks is enough to clear a decent-sized rockfall. Failing possession of any form of explosives, any spell that deals similar damage (2d8 or more) and deals some form of blasting effect will suffice quite nicely (spells which create no such pressure, such as Fireball, will more than likely be entirely useless).
Of course, as mentioned before, such spells or explosives could easily trigger another collapse, and as it may have been guessed, the more powerful the spell, the more likely the backfire...