This guy offers two missions. First you must have completed Sodat's "Confront Emperor Vaakiszh" task in order to request it because it takes place in Silyssar. Second, his faction is broken and you need to sneak to get him to respond to hails.
If you say "venture into Silyssar" you are given the mission "The Source of Shissar Power"
If you say "survive" you are given the mission "Immortal Coils"
I have yet to do either mission so I know nothing beyond the first step of each is to enter Silyssar. Neither of these quests are currently listed here on Alla's