Under the mountain's roof are people using jackhammers to worship the gods. The noise from their jackhammering echos up through the mountain and up toward the sky where the gods live. As long as each person uses their own jackhammer, the sound will be loud enough to reach them.
Unfortunately, the people who live around here can also hear you and the others worship in the mountain and they're going to sue (すう) you for the noise.
Currently there are no similar looking kanji which exist in the WaniKani learning system