In the Pit of Saron he serves as mount to Scourgelord Tyrannus. During the Tyrannus encounter he flies overhead raining down ice upon the players, and flies away when Tyrannus is slain.
Abilities
Mark of Rimefang - issued by Tyrannus; marks a target to be attacked by Rimefang for 7 seconds.
Icy Spikes - Ice spikes pierce the floor and then rise up, dealing 3813 to 4187 Frost damage and knocking up enemy targets within 3 yards.
[Icy Blast]—You will see approx three blue runes drawn on the ground. Rimefang will cast Icy Blast on these runes causing the ground to freeze in that range. Players standing on this icy ground will get their movement speed reduced and be inflicted with 1200 Frost damage per sec while the player remains standing on it. The players hit directly by Icy Blast will be hit approx by 5,444 - 5,691 Frost damage.
Patch changes
Hotfix (2010-02-05): "Rimefang now flies less frequently in all raid formats."