Speak with
Herbold
You will have to find 4 places to step on, be fast, because fire will end!
And if You won't be fast enough, You will have to do everything again!
Go to
Dragon Island portal and find this place, step there
Enter cave above and enter this cave
Find this place and step on it
Go back and now go here
Find and step on this place
Now go to
Herbold place and step here
And finally step near
Herbold here
Speak with
Herbold to finish the quest.