Obligators. This is the first time you see them in the book. It isn't the last time you'll see them, but it's nearly so. They just don't have much of a part in the story now.
I toyed with making them villains in the novel, involving them a lot more in politics, but discarded that concept. I decided that 1) The Lord Ruler's power was broken, and that fighting against remnants of it would be a little anti-climactic. 2) There just wasn't any more space in the book for more villains.
The armies invading Luthadel, and their leaders, are bad enough. Part of my rational is that the warlords–not the priests–are going to be the real danger in this new world. The priests were a force for stability. Now that everything has been overthrown, they simply won't have any power to be of a threat.
Though, I will note that a major force in the third book is, indeed, an obligator who has taken control of a section of the empire.