Mega Man firing thunder from his Mega Buster.
To shoot three bolts of thunder in differnet direction, destroying foes.
Thunder Beam is a weapon that allows Mega Man to transform into a yellow and gray attire. This allows him to shoot three thunder bolts out in three directions (one upward, one straight, one downward). This is useful if Mega Man is surrounded by enemies.
Mega Man used Thunder Beam when facing Elec Man. (MM #3)