Enki is similar to Enlil, though with a few thousand more HP and a higher Strength. The Aqua Ring you found can protect you from its Magic attacks, and Thunder is your best offensive spell. Deprotect, Deshell, and Poison are also extremely useful. Be careful, though, as both of these bosses have powerful attacks and abilities. Bellow will add a number of positive effects as well as negating your debuffs, but they can be quickly recast.