Froglok berserker  

Both cycles have NPC's in their cycle that when killed set up a 3 day respawn. I.E. it was designed with some long respawns in it.
Ngreth Thergn

I killed this guy a lot of times, I'm guessing about forty, and all he dropped was money and high lvl research stuff. But I did get a Blue Diamond off of Frayk, I think he is a shaman. Dont try to find these guys if you don't have a tracker, its hard to find them and you might run into those little Black Ravengers that are red to a 40 and hit for over 200.

These guys are freakin' cowards. 90% of the encounters I've had with them are right after a battle and I'm medding. They've never killed me, but I'm usually in no condition to kill them and have to run away. They con dark blue to my 28th lvl shaman.

so could a lvl 24 war and a lvl 38 war take him

This is the big guy, the one you are going after, the big daddy. He drops high level gems, high level research as in 49 stuff, the high value jewelry that has no stats but sells for 85-145 pp each sometimes, and always drops pp around 2-9pp is usual.
The research stuff is uncommon, and the jewelry and gems are rare. Possible Gems that I have recieved from him are Ruby, Fire Emerald, Sapphire, Black Sapphire, Blue Diamond even!

There are 2 yes, 2! Froglok Bererkers. When one is killed another Froglok berserker, Frog Ranger, might spawn or one of these level anywhere from 20-30 monsters,

Blackbone, Iksar Skeleton undead
Bloodgorge, Leech
Bloodvein, Mosquitoe
Deadeye, Iksar
Dreesix Ghoultongue, Frog Shaman
Ebon Bloodrose, Plant
Farik the Vile, Iksar Shd
Fakraa the Forsaken, Iksar Shd
Fangor, Thing
Frayk, Frog Wizard
Froszik the Impaler, Frog
Gorge, Thing
Grimewurm, Leech
Grizshnok, Iksar Skeleton Undead
Heartblood Fern, Plant
Soblohg, Frog
Two Tails, Thing
Venomwing, Mosquitoe
Weeping Mantrap, Plant
Zagran the Mad, Iksar Monk

Those Named guys are just to annoy you and delay you from killing the berserker. Some are pretty tough, for example Frakaa the Forsaken, who is a Shadowknight, Harm touches you for about 271-301. I am pretty sure that is not every single one but there is probably like 1 or 2 I might have missed.

They all wander. They do have specific starting points but I have not taken the time to find them out yet, since you have to be fast and run to the next one before he starts to move.
It is best to be a Ranger or Bard hunting these since you can just melee them and have no down time, always tracking the next victim. Druid would have downtime but could still do fine tracking. Then you could partner and make it a little quicker, but that takes coordination which I personally haven't seen very many people have it good.

Hope this helps everyone, please tell others to read my post too!

Killed one of these yesterday solo with my 30th ranger. It dropped over 5pp in coin and a Word. Don't know if I just got real lucky or if they always drop around this much. Been hunting quite a bit in the Swamp and have only ran into one of these...

The froglok beserker is fairly uncommon, at least as a wanderer. Has a pretty good healing spell, so watch out if you get one of these while fighting a froglok warrior.