He managed to convince two of the eastern lords to go with his plan. The fool seems to think he can strike a deal with the Forsaken by turning Greymane over to them.
Listen carefully, <name>. We need to resolve this with as little bloodshed as possible.
This potion will allow you to sneak in undetected. We need you to assassinate the traitorous lords before this gets out of hand!
Progress
Careful, <name>.
Completion
I wish it could've been avoided, <name>. Let us ensure this is resolved without further bloodshed.
Get close to the Reach and use the item. Ignore Genn, as the two named mobs are past him. Lord Walden is north of Genn's position at the house marked on the map, while Baron Ashbury is at the lighthouse far to the east. Watch out for the Mountain Mastiffs — they have Truesight and will see through stealth. Attack the named lords when they are far from any watchmen, as they hit hard. Stay in stealth while moving around to avoid any unnecessary combat and head back to Genn.
Rogues don't have to use the potion, as they have [Stealth].
On complete:
King Genn Greymane says: It's over Godfrey. You have no support left among the eastern lords.
Lord Godfrey says: No... I'd sooner die than have one of your kind for a king!
Lord Godfrey runs to the west and jumps off the cliff, committing suicide!