Definately seemed a bit easy once I got some drowns and a cultist up. Played a Monarch game. Only Hyborem attempted a landing, he brought 5 caravels, 1 made it through my net and he dropped a lonesome diseased corpse.
I basically built up 2 drown and a cultist to eliminate two of the the Sheiam stooges, of course transported with Black Wind. When they eliminated the two civs up north, I brought that group back, one of the Drown died to a 98% win chance ;( While that expedition was underway, I was working on a second army for the southern expedition. I got a lucky event that gave me a Stygian guard, so I sent him to the southern islands to nab some xp then when I got Saverous and another cultist I grouped them up and went to finish off the game. I did lose Saverous to Abashi with an 88% chance to win but the Stygian guard with him had a 75% chance to win before Saverous damaged it, fortunately he didn't damage him too much so I got a 99% chance to win vs Abashi after Saverous died, after killing Abashi it meant it took a few extra turns but despite 4 Balors & 5 Longbows it was 99.9% chances to win.
I only encountered one extremely dangerous situation apart from Hyborem's attempted landing which was easily crushed only 1 diseased corpse landed; as I approached the Sheaim that started on the island, with a Drown, Stygian, Cultist and a fair winds adept I got within 4 tiles for his stack of caravels to attack my Black Wind, fortunately after killing 5 of his caravels he retreated back to my capital area with the entire army intact...it was a loss that only cost me healing time and the trip back out there. Of course when it happened, it was also quite Ideal as Saverous had 4-5 more turns to complete...so three to heal up two waiting for Saverous so I could swap out the Drown.
Although I will say, I used to prioritize Ritualists...I certainly fear Cultists more now...fortunately however AI's tends to attack with them recklessly before using their spells. I reckon starting cities should be place inland so you can't clear the map with a cultist. Yes I got Saverous and a Stygian guard but I could have done it just as easily with exclusively drown as my attacking force, though it may have taken a a bit longer if I'd done so.
Fun game nonetheless, I rarely play OO in my normal games and only did so to avoid the healing issue in this map, it was far more effective than I possibly could have imagined.