How did the Jailer rule the Maw despite being chained up?
The reason for that is quite simple: The Runes infused with Domination(which is the same Magic used by the Drust) which are also the means by which the Jailer controlled the Helm of Domination(which utilizes the same Blue-Black Magics of Thros)!
The Jailer was thrown into the Maw where he wouldn’t use Thros the Blighted Lands’ Magic on the rest of the Shadowlands!
The main problem with the system was that the Eternal Ones failed to account for the original Realm of Domination(Thros the Blighted Lands) which wasted no time getting the Runecarver to create more Runic Weapons of Domination that would be bound to the Jailer!
The denizens of the Shadowlands automatically list Thros’s Magics as Maw Magic when in reality Sin-Touched Death is the Maw’s Magic!
If they were told that Thros the Blighted Land is the source of Domination Magics and any Runes the Jailer used could have come from there Devos would have probably contacted the Drust instead of the Jailer.