So it's my understanding that the only way to kill a guardian for good is through the use of some kind of Darkness shenanigans (like the Hive do) or by erasing us from time (like the Vex). But the Cabal can't kill us because they haven't found a way to extinguish our Light. So my question is this: how the heck did hundreds of guardians die for good at the Battle of Six Fronts? How do the Fallen kill us? Edit: Thanks for all the great replies! I get it now :)