I had a very successful Wither Training run last night. I started with 15 Withered (1300 is my cap still, need to spend some times doing the main Suramar Quest), and ended with 20. I inched through, luckily avoiding Dro, and opened doors until I got to 400+ points. Then I went back and grabbed some chests-one 5-Withered and 2 10-Withered in total.
I tried bandaging hurt Withered, but they didn't seem to gain health this time. My average Withered health (mouseover the Withered Commander buff) stayed the same. Perhaps this changed since last time I did this quest.
Arcane anomalies are much easier with 15+ Withered, as you can stun their death-explosion and turn on the Mayhem! buff to finish them off.
I'd gotten the item that makes the Withered less likely to flee last time, and it was noticably easier to keep them on task. I think I needed to chase 4 total over the course of the run.
I ended up with two copies of Spellmask of Azsylla
, so I hope that means I have 2 spell-mad whatever. Though I know I won't and I just got boned.
EDIT: on the above point about the Mana-Rager chests, they are always static. I just happened to choose two Mana-Rager chests, and they were both marked as my first one so they dropped the same hat. I'll check when I get the WQ next to see if I have 1 or 2 Mana-Ragers.