ToME: the Tales of Maj'Eyal

So, I finally got far enough along with a necromancer to use Essence of the Dead-powered Assemble. I got a second bone giant as advertised, but it refused to move. I spawned it in an Intimidating Cave in Daikara 3. After auto-exploring the cave, its Reassemble procced, but it left my party. I tried again, and this time both giants followed me properly. One of them died and Reassembled, and it left my party but remained friendly and continued to follow me. I haven't the faintest idea what's going on.

Update: As I feared, when I left the Intimidating Cave level, my extra bone giant disappeared.

Your Re-assembled Bone Giants vanish from the party rooster regardless of you having Essence of the Dead and won't follow you when you change level, I've reported this before. On the bright side of things, you can enjoy this while it's not fixed by repeatedly Assembling, then Sacrificing them.

Oh. Well, then. I admit that the thought had occurred to me. Wasn't sure if it would work.