Your best bet than is to avoid the water like a plague and use your boat as a killing machine.

Since its hindering terrain, a row of nightstalker*** in front would do well.

followed right behind by a row of Magic blasters(to fire over the Stealth guys, and to hit opponents stealth guys). Finally I would put a healer behind.


Can you move the boat, and shoot the same turn?
if so its like a long ranged bounder/tank

Just wanted you people to know what I went with. My army was:
1 Magus
1 Elemental Priest
a bunch of * and ** Longbow Archers
1 Podo
1 Imp*

Place the Archers in a Death-Star like formation around the Priest and Magus for 18 def and Enhancement. Lots of people used Iron lungs and even Water Minions, but the range on the Longbow Archers kept them far away. Move the boat near the island and move the formation and they can't touch you. I won the whole thing too, :D