After a newly regenerated Third Beginner was attacked by the Fire Clan and crashed onto the ice portion of the planet, the Beginner stumbled across their base. Speaking to Lucia he revealed his friend the Doctor and decided to finally attack the Fire Clan.
However after the Beginner destroyed the Fire Clan using the Doombringer, Lucia turned on the Beginner and the Doctor and went to execute the Doctor for preventing genocidal methods of ending the war earlier than it could've. But Zarr, angry with the conditions she kept the Ice Golems in, stepped on her and killed her. (When Worlds Collide)