Thunder Wool

Thunder Wool (サンダーウール) is Sheep Man's special weapon in Mega Man 10. Mega Man launches a thunder wool-cloud that slowly rises, and a lightning bolt shoots straight down from the cloud. He can fire up to two consecutive shots. The cloud itself does very minimal damage. Pairing two clouds together will increase the lightning strike area and power.

Thunder Wool is Pump Man's primary weakness - a single bolt from this weapon can not only penetrate and dissipate his Water Shield, but can also strike Pump Man in the process. It is also effective against the Weapons Archive when it copies Tornado Man's data, Crab Puncher, and Block Devil.

Damage Data Chart
Known damage values in units for Mega Man 10.


 * For Thunder Wool, the first number is contact made with the cloud; the second number is the lightning bolt. 

Bosses weak against Thunder Wool

 * Pump Man: Mega Man 10
 * Weapons Archive/Tornado Man: Mega Man 10
 * It also does considerable damage against Crab Puncher and Block Devil.

Trivia
It has been buffed in fangame [megamanmaker.com Mega Man Maker]. 
 * The Thunder Wool is commonly considered one of the worst Special Weapons in Mega Man history by some fans. The most common argument against the weapon is that its high energy cost does not account for its difficulty to use, and the area and power of the cloud and lightning strike.
 * The Thunder Wool has the same color scheme as the Thunder Beam. It is possible that it was done as a throwback to this weapon, as this color scheme has not been used for an electric weapon since the first game.