Twice during the DE “Kick the Nightmare Court out of Quandry Scratch” in Mount Maelstrom I was downed (due to the respawn rate being more than I could handle solo). Both times, I managed to kill a Nightmare Court Spider, and did not rally, leading to my death.
The second time, I had managed to kill all Nightmare Court Courtiers nearby first and the spider was the last opponent left. Again I did not rally and the nearby thornpod objective finished me off before I could get back up with my #4 skill. If the spiders are some kind of summon-like sub-creatures of the Courtiers, and therefore by some cryptic logic not “ralliable”, then they should have despawned like normal summons or pets when I killed their masters.