The Insequent are a mysterious race of people who dwell to the west of the Land. Each Insequent has a unique and very focused skill that can seem magical or superhuman. These skills range from invisibility, virtual invulnerability or even time travel. They have an almost dismissive disdain for the Haruchai and a bitter and long-standing rivalry with The Elohim, which has not yet been fully explained. They rarely reveal their true names, but prefer to be identified by their titles. So far only four Insequent have appeared in the stories: The Mahdoubt, the Harrow, the Theomach and the Ardent. A fifth, the Vizard, is referenced by several other characters, and a sixth--the Auriference--is mentioned briefly by the Ardent, although both the Vizard and the Auriference are believed to be deceased.
The Insequent first appear in Last Chronicles; where it is revealed that an Insequent played a key role in making the Haruchai the way that they are in terms of their unwavering loyalty and desire to prove themselves.
The Insequent are all very lorewise; at least in the area to which they devote themselves. They rarely if ever use their true names because if someone else knows their true name they gain power over the Insequent. Instead the Insequent use titles in the place of their true names.
This is not entirely true. I dont have the book (borrowed it from a library a long time ago, and it is also apparently not mentioned in this wiki), or i would look it up and create a proper wiki article, and include his name, but the strange guide that led Covenant and his daughter Elena to the blood of the earth was also an insequent, although his association with that race isn't made apparent untill the existence of the insequent themselves is revealed in the last chronicles.
The book left several clues to this, not the least of which was the guide himself mentioning the "loss of name and use and life".
The Haruchai also react strangely to him, as if they are aware of what he actually is, when he first appears to the council of lords, but refuse to elaborate on their apparent knowledge when asked by the lords.
Apparently, he was a servant or accolyte of High Lord Kevin, who must have known his true name, and commanded him to assist the high lords in finding the last of his wards, the seventh (the blood of the earth), but only to help them if they knew the right questions to ask. He died shortly after his purpose was served, uncounted years catching up with his un-aged body.
(You are referring to Amok, the being created by Kevin to guide the masters of the Sixth Ward - indicated by the bringing to life of the Krill - to the Seventh Ward, i.e. the Earthblood.)