At the start of the quest High Tide, speak to Osh (Cobalt Scar) and receive a blessing from Prexus. This blessing increases your stats to the point that Salton can be soloed. If you die for any reason, you have to speak to Osh again to receive another blessing!
During the fight, Salton will emote that he "feasts on a nearby corpse". The corpse will refill his health, and he'll emote that the corpse begins to glow. When this happens, back off a long way before a large AE damage effect (121000)
Although he refills his health each time he feasts, his total health is decreased each time, making it easier to kill him before the next feast.
Joust him and pull him deeper into the tunnels where he has nothing to feast on.
He may be bugged, during one fight he continued to chase during the 'casting' phase of his feast making it impossible to reach a safe distance. On the next encounter I did not attempt to snare him and it worked correctly... so 'snare' might be the problem.