Valderly

"I invoke...Winter."

Valderly was a master waterbender, who acted as a General of the Water Tribe, a descendant of his well-respected ancestors that honed their skill in the finer arts of waterbending for decades. Inheriting these skills, Valderly rather easily became a commander in the armies of the Water Tribe. Perhaps the most famous feat performed by him was his usage of "Winter".

Battle of Silent Pass
General Valderly participated in a war known as the War of Succession, following the assassination of the Fire Lord who was succeeded by his best Marshal in a brutal competition between many commanders for the throne, killing the rightful heir, the son of the Fire Lord. As such, the Water Tribes and Air Nation, who were allies, all declared war on the Fire Nation to remove the new Fire Lord from his position.

A combined force beneath General Valderly of the Water Tribes, Hoinker of the Foggy Swamp Tribe, and Xiao of the Air Nation was sent into southern Fire Nation territory in a mountainous area known as Silent Pass, in which was a wall of rock and mountains before a river, and a single, much larger mountain overlooking the pass. Behind the wall of mountains stood an army beneath three Generals and one Marshal, named Marshal Clarke. On the other side, behind the long river and in front of the large mountain, were the Air Nation, Foggy Swamp Tribe, and Water Tribe armies.

Valderly commanded his troops with expertise, setting up the defense in favor of the Water Tribes even though he was within Fire Nation land and unfamiliar with the territory. However, unbeknownst to him, the Fire Nation had kept up the illusion of a smaller force, when really their army was much bigger than seen to the eye due to the fog and mountains of the pass. Furthermore, the Fire Nation possessed lightningbenders, who immediately began to turn the tide of the battle as the black clouds above the battle empowering the waterbenders with rain (and dampening the fire) began to shower lightning onto Air Nation and Water Tribe men.

Seeing this, Valderly put an end to it by stopping two gigantic bolts, one from the clouds and one from Clarke, freezing them using his powers over ice and shattering them. This development shocked Marshal Clarke, who soon began to engage Valderly on the field. Freezing and melting the ground beneath them, they exchanged blows, fire against ice, and remained on a relatively even stand until Valderly summoned his spirit manifestation around him.

It was then that Clarke revealed that he possessed an ancient form of Firebending, known as Sunbending. To demonstrate his skill and destructive power, he sent a strong beam that shattered Valderly's manifestation. This caused Valderly to remark that Clarke was powerful and impressive, but he too had ancient tricks from his ancestors.

Using a move that his master taught him, passed down from generations, Valderly invoked the spirits of winter, freezing over the entire battlefield and causing a raging flurry of snow. The blood in Clarke's body as he was bound began to slowly freeze, causing him to realize that he had lost the battle. Clarke surrendered to Valderly, who, out of respect, spared his life, allowing him to live.

Aftermath
The victorious General Valderly, after winning the battle of Silent Pass, continued to lead the Water Tribe forces through the Fire Nation, assisting in finally removing the Fire Lord from his position. Having won the war with his allies, Valderly returned home. He was promoted to the rank of Marshal and gained an advisor status to the chiefs of the Water Tribes.

Death
In a later war and battle against the Earth Kingdom, although it is unknown when or why, Valderly was killed by Marshal Vraxx, melting him away with lavabending.