Morthul, Mountain Terror

When Morthul, Terror of the Mountains enters
the battlefield, destroy three target mountains.
For each mountain destroyed this way, its
controller creates a 0/4 colorless rubble artifact creature token with "{t}: Add {c}"
Giants you control get +2/+0 and gain rubblewalk (they can't be blocled if the defending player controls a rubble)
"Uh-oh" - Horth Guard Captain, last words