Here's another one:
Luckily, I got pillars done on the first try, but barely. In fact I thought that I'll need to reprep stuff, because I got the message that the first pillar have respawned right as I killed the third one, but apparently that was good enough lol. The only weird thing that happened because of that (I guess) is that mobs in bases didn't die, but that didn't really bother me much.
In the main fight the Reavers and Fire Elementals never did enough damage to make me bother with killing them. I just prefered to DPS Velah full time to nullify her regen.