What is your business this time?
#b1) Do you know anything about a ghost tree?

A ghost tree... I guess you're talking about Stumpy.
#b1) What is this Stumpy?

It's a very old tree surviving all the years ever since [map 102000000] was covered with lush forests. As it weathered all the pains and tough times, its anger grew large. It was infuriated at the people destroying forests, and at the scenes of forests falling barren.
#b1) What happened next?

In the end, the rage turned the tree into a monster. Now it's nothing but a horrendous monster gobbling up nutrients from the soil. Don't go too far into there. I'd praise and encourage your curiosity, but it is the king of all stumps. You should never underestimate its power.