The Contingency Plan That Failed.

When he was ready, he advised the Will of the realm, "Think of the benefits as you undergo this painful process so that you can hold on. I know that you don't have mortal feelings or weaknesses, but you might need the motivation. Find a way to motivate yourself so that you can survive. Think of your children if you must. Either you survive or you will explode, and they die."

The dragon king then explained what was to be done to the sapling. The landmass was then pushed into the sapling. Most saplings are bigger than the landmass, but they always explode when they try to assimilate the indestructible fragment into their existence. The problem is not a matter of size. There's just too much of a difference in their state of existence.