Lord Ssardak was an Ice Lord who led an attack on Trenzalore to destroy the Eleventh Doctor and prevent the new time war. He cocooned himself in ice and travelled safely through the planet's atmosphere before crashing into the snow, seemingly nothing more than a meteor. By only wearing his body armour, Ssardak was able to avoid detection by the Papal Mainframe. Once he'd landed, he punched through the remainder of ice and found his soldiers, Essbur and Zontan. He enlisted the help of a local resident, Elias, to help collect pieces of a sonic cannon that had fallen to Trenzalore disguised as smaller meteors and used the Truth Field to ensure that Elias would not betray him.
Unbeknownst to Lord Ssardak, Elias was actually the Doctor in disguise, who had evaded the Truth Field by avoiding Ssardak's question about his identity. He planned to kill the Doctor by using the sonic cannon to create an avalanche that would bury Christmas, but was killed along with Essbur and Zontar after the Doctor tricked the Ice Warriors into revealing the frequency of the cannon. The Doctor then used his sonic screwdriver to amplify the cannon, causing it to explode, destroying the Warriors and instantly vaporising the ridge they were on. (PROSE: Let it Snow)