They should run into each other and fight inside the gem!! High stakes! Kirei would easily assume Dorian won't be trying to influence the gem in any good way and would go after him, though, yeah. (I'm also cool with fighting on the battlefield! Gods dropping in, woohoo)

EDIT: Yeah, let's have them fight in the battle outside, to start! I want to set some threads there.

What brand of nightmare fuel do you want... I sort of really want Kirei to show Dorian his family memories.