Ssardak

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 traveled safely through the planet's atmosphere before crashing into the snow, seemingly nothing more than a meteor. By only wearing his body armour, Sscardak 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 the Doctor pleaded with them to leave Trenzalore instead. Ssardak realized the Doctor's plan to amplify their sonic blast with his sonic screwdriver only moments before it happened and he, along with his soldiers, were killed in the backlash. (PROSE: Let it Snow)