How to Solve
WyvernSource Guide Currently out of date and incorrect as of April 22, 2020
Go to Iss’rano, which is north east of NV by all the lava and the crevice.
Once in town, search the buildings for a key - you will need it later. After you find the key head to the east where the map starts flickering, then into the next map where it will be all darkened out.
Go into the mansion and take the stairs down. There will be another set of stairs here leading down as well. Take these stairs and follow the map. you'll have to fight a vampire miniboss. You are looking for a grug to talk to in the room after the vampire. DON’T TAP ON, YOU WILL END UP KILLING IT. Go beside the grug and type "talk ring"and she will give you a ring.
Once you have the ring head east two maps until you find a fiery portal and enter it.
Along the way will be numerous skulls as well as coiling grass traps. Sneaking will disable these and flying avoids them altogether. Having both is probably preferred.
Once you go through the fiery portal there will be a map with more skulls in it and three RDs. Which RD you need is random, but you only need to go down 6-10 levels. If you haven’t found the “lair” by then you are in the wrong RD - go back up the stairs and try a different one. Recall / word of recall doesn't work, so you'll have to traverse the floors back floor by floor.
Once you get to the lair, there will be more skulls as well are fire elementals and some lava, run to the east as far as you can and enter the portal with the “Strange markings.” You won’t be able to enter if you didn’t get the ring from the grug.
Inside you will find the Boss monster, a glass serpent. The serpent will cast blindness a lot, as well as a lightning bolt. He will also cast dragon breath, so have your fire resist ready. He has tons of HP as well as being pretty magic resistant, but you can take him out will a crossbow if needed. Once dead, loot his body to get a “Blackened twisted heart” and return back to the town.
Once in town give the heart to the priest in the church.
Coiling grass traps
Boss - a glass serpent
Things to Keep in Mind
The resists that you will need here are fire, paralysis, slow and confusion, maybe some shock too, the most dangerous enemies are skulls and the end boss.
Flying or sneaking will avoid getting trapped in the coiling grass.