Best method I've seen is get a bunch of guild members to the point where they all need the part where you kill X conquerors, form up a raid, and just WTF own anything that spawns for ~ 1hr or 2. Treat it as a raid trash throwback event and bang out for as many as you can.
Conquerors is share spawn with other ogre such as spellbinder or commander. But spellbinder and commander have too much hp, maybe more then named. So, no one want to kill them, that is why conquerors are rare.
I just noticed that the group mission " Final Fugue " has a lot of trash. Might want to see if the conquerers there count for the Even Shadier Neighbors quest. If so then you might be able to get several "free" spawns just by getting the group missions.
Unless my group was mistaken, mobs can outright change to lieutenants (we could swear we saw it for these) and conquerers. Make sure everyone in group has the task. I want to say we saw lieutenants frequently in the north wall of the zone and conquerers more often near Dokk (our camp for those was on the north side of the west wall camp).
