[Hellstrom]

Actually as spelled out in this thread, http://thaypw.org/showthread.php?tid=1517

Once a 'mortal' pledges to the Vengeful at the tomb in the Bezantur Crypt, that person will always be saved (i.e. - have unlimited respawns) by the Vengeful. However, if someone has not pledged at the crypt and runs out of respawns the normal way, when they end up on the Fugue the only way to return on their own is to take the Lich skull from Brianna which turns them into an undead creature. Likewise, any undead creature returned from the Fugue will then have unlimited free respawns from the Vengeful once again.

Ishanti could go to the crypt, voluntarily pledge herself at the sarcophagus (which will change her deity to Velsharoon and cost her the normal cost for that AFAIK), and she will not turn into undead, but will retain her normal appearance.