I also have the spots marked and it seems they spawn every 2 hours of game time, but I have not figured out what time it starts from? Server up? Last couple of times I could not even target the Shadowlord as he was immediately surrounded by mass amounts of Pets and People and Dragons seem to block ctrl-shift as well.
Info:
Spawns 3 locations:
1) Wastelands (Inu hut)
2) Mt. Sho (Volcano)
3) Lady of the Snow
Times: Every 2 hours, but when?