Find Vin Moltar in the Qeynos Aqueducts. He is around level 23-25 and you have to kill him. Once you kill him loot him for a container. Go to Kerra Isle and find Melixis. She is hidden away in a hut near the village area. When you hail her she says that she has found 3 shiny rings from all of the world. The dull ring, a kinda shiny ring, and a really shiny ring. These are the copper, gold, and platinum rings for the Paw of Opolla Quest. She ask for bracket mildew for the dull ring, faerix spores for the kinda shiny ring, and degenerated guk week for the really shiny ring. The faerix spores and degenerate guk weed are very very rare drops off of the fungus mutant located in Upper Guk. It's hard to explain where it is, but the loc is 500, 200. I go there from the swamp zone to heart/large/giant Spider cave, to Froglok Scryer area, then to the hall where square pillars are. Keep going Northwest and take the left path at the fork. You'll come out in a big open space with a rather big pond on the right, and you'll find yourself standing on a path that's higher than ground level. There is a ladder coming up from the waters area to this path, and you can use that to confirm your location here... Once you're there, all you have to do is to jump off to your left from that path. Don't jump off to the water's side, which would be on your right. You'll take about 10 damage from this fall - not a big fall, and you'll find yourself standing at the corner of Fungus pit, where all the fungus spawns. This is the easiest way to get there, I think. Remember, though, you can't get back out from the way you came, because you took a shortcut by falling off the path. (Thanks to Carline for the directions) He is a shadow knight and is level 25. The spawn time is approx. 17 minutes. He is fairly difficult to solo because he is a druid and casts sow, dd spells, and dot spell. He only has 650 hit points though which is one of his weaknesses. After you get these three items from the fungus mutant head over to black burrow. In the razorgill pond at the very bottom spawns the last ring, the silver ring. The spawn time is two hours so hope that no one has already taken it. The razorgill in the pond are level 4-8 and can't see invisibility so they shouldn't cause a problem. Now go back to Melixis and give her the items she asked for one by one. Once you have all four rings, put them all in the container (make sure it is the right one) and press combine. You know have the Paw of Opolla. Click here for map of Upper Guk.
Note from KFling - Just finished the quest last night and got the silver ring in BB got the copper ring from the guk mildew dropped by mutant fungus (is common) dropped about 6 times in 7 and half hours, and got the degenerated guk weed once in that time, and gave both the guk mildew and degenerated guk weed to Melixis in Kerra isle and got copper and gold rings, and got plat ring from Gynok Moltor in Befallen named mummie, took me a total of 55 hours to get that ring, five days of 10 hour camps. And I have also been told that Muntant fungus will drop the fungus need to get silver ring from Melixis but have not confirmed that. I got mine in BB in the pond. (Thank you for the Note KFling - Aline)