My knowledge on Rhugol: => he does enrage at 10%. => he doesn t flurry => he doesn t cast but banish. => he can be snared and slowed. => he hit for 500 max. => he run away at 1% hp.
Pull secret: Pull him in the jail where he banish, it s long but make the fight easier.
The easiest way of dealing with these guys (because of their banish proc) is to use pets and range attacks. Send a pet in as your MT, keep all healers on that pet (or have healers /assist Praesertium to see which pet he's on to heal that pet), have everyone else use their pets on him to push him into the corner. Melees use range attacks only, nukers and DoTers are your friends here. So long as the pet has sufficient agro, noone should be banished and the mob should go down with no casualties to your groups.