ToME: the Tales of Maj'Eyal

I unlocked the Zigur Sacrifice birth gift today, and can't figure out how to activate it, or what it does. I checked the wiki and looked around the character creation screen, and found nothing. What is it and how do I use it?

Okay so, if a character (any character) from now on DOESN'T have spells (including runes), and they come across an 'arcane' escorts (lost seers, anorithil, sun paladins, alchemists, etc), they can betray the escort instead and get the appropiate antimagic style reward instead of the traditional offerings.

Ah, that makes sense. Thanks for the info!