I'm a level 30 warlock. I have killed Urzok solo using Murmur and Super Good Advice plus loads of grenades. When the public event started the first wave was fallen enemies. I ran away from the warsat and didn't kill any fallen enemy. By that time a second wave of hive enemies spawned. I killed all of them. By that time it was total chaos since there were plenty of enemies. When Urzok appeared, I used Murmur to take down his shields and used SGA on him along with plenty of grenades using radiance. In addition, I killed the other hive enemies. All the fallen enemies were now attacking Urzok. I died twice in the process but still took him down within the time limit. The shielded fallen captains were a big help.