Can commanders just disappear?

[Endoperez]

Also, because damage due to disease occurs in the very end of the turn (the same time units usually heal, after all battles etc), you could cast something like Send Lesser Horror to cause a battle in the province she's in, and have her cast Heal and/or personal regeneration. She might be wise enough to target herself with the heal, and the regen should at least keep her alive for a few more turns.

[Sombre]

I find the AI prefers to cast heal on guys with no hp loss or injuries whatsoever. Har