Well, since this thread has been bumbed, I might as well post that I actually didn't have any intention of attacking Lanka. I was planning on building up to some heat-resisting spells and throwing cold water (Hah!) on Abysia's fire with buffed Deep Ones (100% fire resistance, hah! Again!) Not to mention, my start was rather nice because I don't think I had any competitors for the sea and I had easy land access. I could slack off and still survive reasonably well (I actually only had one fort by turn 14, though I had plans to get another; I simply didn't have the money).
I wasn't sure what to do with Arcoscephale on my border, though. They never contacted me. I guess they took my short message as a warning. Deep Ones only want friends
(well, and food, but don't remind them of that or you might lose an arm).