Really, until we start doing Storm of Magic type things we shouldn't even discuss stuff like this. We'd need a Pact Army (A warband of supernatural allies that'll show up to throw down when reality starts coming apart at the seams, presumably using the aforementioned loose reality to do so even if you didn't know this was going to happen; The Empire can stand being cautious allies with individual Tomb Kings, according to the battle book) and Cataclysm Magic to even get up to the level of the average Patriarch, and while Thyrus Gormann can call Manaan 'a watery, damp squib of a little God' and mean it that doesn't mean he could stand to be the center point of a religion in turn; being a god is a matter of spiritual nature, rather than power.
(Magister Patriarchs may not be gods, but I'd bet on them versus anything but a personal manifestation of one.
Of course, 'the personal manifestation of a god' is something that needs describing in order to underline the scale being discussed.
Norscans are said to worship Manaan under the name Mermidus, a cruel and terrifying bloated corpse large enough to stand on the sea floor and reach up to the surface, that resides underneath the Sea of Claws and drags ships to their doom. They perform regular human sacrifice to take the edge off of his hunger.
The average depth of the sea is about 12000-ish feet, so we'll say two miles. That's utterly insane, but has the benefit that we don't need to apply the 'of course, he's a god, so he's stronger than he looks' modifier; a revenant two miles tall, of roughly human proportions, is plenty of power for a god's full strength.
Thyrus Gormann is good, but not that good.)
