O.K. (sigh....)
assuming the dragon isnt defective OR stupid......
LM is probably right. anything else is not enough. especially if the dragon is bright enough to understand tatics.
So, feed it an explosive. In RM? most trap spells arent powerfull enough. However,.....
One party did it with a 6 month ritual trapped just before compleation by a ramped up spell off Ritual Mastery. I dont remember the item, but they had to quest for it. (Hand of a dead god tied shut with bands of iron from the pit of hell ? ritual stored within ? dont remember.)
The ritual was a nether ritual designed to have a flaw in it. It took like 40 casters to keep the spell going and 5 of them were the 'prime' people. I think it figgured out to like 200,000 power points.
I allowed the casters to disengage themselfs from the effect of the failed ritual by increasing the research level of the ritual.
Once finished, they surgicaly implanted it inside a cow. Then just placed the cow and waited. They may have sheilded the magic with one of the alloys out of Alchemy comp.
Need it be said no one "lives" ANYWHERE even close to the devistated area.
(and yes they went up a level for compleating the task as well as those earned while setting it up)