The problem is, the weighting never seems strong enough. Every single time I play with the sheaim on the map, "someone" else (ok yes quite often it's me) discovers RoK, then sailing, then before I know it the single sheaim coastal city has the religion and they've converted. A couple dozen turns later they've beelined AV, have the holy city, soon all their cities are AV, but they are STILL worshiping kilmorph. Even if it's malchevic and he's gained the spiritual trait from getting AV and so doesn't have to contend with a 1-turn revolution.
Actually Keelyn is a very good little devil girl, and does convert to AV quite often, even though she doesn't seem to bother going for corruption of spirit herself. Of course, lorewise, it does become clear in the scenarios how Keelyn is the best of all the FFH leaders when it comes to hell, but I digress.
It may become necessary to use worldbuilder to remove non-AV religions from the civs you want to convert. Also, if you want a fun-filled helly game for christmas, I'd recommend not having the cualli. It's great fun to fight them, sure, but once the counter hits 50 all their beautiful productive marsh+jungle+swamps turn into useless blue stuff (shallows) if hell terrain is hanging around.
I'd say the sheaim are absolutely essential though, even if they don't go AV. If only for the Elegy ritual to help armageddon.
Challenge mode: worldbuilder someone Infernal Pact on turn 1. Then watch hyborem take over the world from the start
