In Rathe Mountains
Other PHs that spawn in that same cycle
Bunk Odon
Fandl Arathin
Gwynn Marthank
Tal Godin
Tann Cellus *
They are inside the 3 part big Inn (not the huts) and they spawn in the southern room. The two merchants in the room do not attack. The PHs stay up for 45 seconds (*Tann Cellus and Rell Ostodl cast buffs and this causes them to take 3 minutes 25 seconds before they despawn). Placeholders will attack you if you're sitting. If you kill the PH, it takes 6 minutes 40 seconds to respawn and the cycle to resume, so don't start doing that :)
When they despawn, a new one pops up very quickly.
Long cycle before we saw Sir Edwin Motte. It was about 40 minutes to an hour before we saw Motte.
Very fun little cycle