[Evilhomer]

I have only played one multiplayer game with MA oceania (slow 10 Player) so my experience is a bit limited. I did however end up winning that game, defeating Amhazair in a spectacular end game with seraphs and other nastiness =).

As to pretender I went with an immortal master lich with some magic in all the paths the nation lacked for a stronger end game. This is not a must, but I do strongly recommend you to have high astral access on your pretender (Reason: strong clam nation with no astral mages).

MA oceania measures up very well against the other 2 water nations. I never had the opportunity to fight atlantis in game I played, I did get to fight R'lyeh however. The key to winning that fight is to get access on the spell antimagic (my teleporting immortal pretender helped with that). As always various underwater buff spells like shark attack, friendly currents etc are important as well.

Your first research goal should without a doubt be thaum 2 (haruspex). The reason is that the ocean floor has a lot of kelp fortresses that you want to get for free. In my game I found about 6-8 early fortresses as well as securing a healthy nature income by turn 15-20. Not having to shelf out the gold to build these forts are obviously one great early advantage (resulting in more early mages and high resource troops). After this I would go conjuration for shark attack and voice of tiamat (you want lots of water income).

One thing that is something to keep in mind from the start is the fact that MA oceania mages sucks when they go ashore (getting penalties in their magic paths). In fact I cannot think of any nation that has worse mages above water. Any good dominion player is going to tell you that magic is vital in winning the end game. So in the late game "land" fighting you are going to need a good gem income so you can summon mages to help your national armies.

The path to victory if you are playing for one is in my opinion easiest achieved by these four guide line steps:

1. Secure the water (eliminate Rlyeh/atlantis)
2. Establish a strong clam economy
3. Put up the nexus
4. Summon a lot of mages to help you (including seraphs through wish) as well as tartarians and other good summons.

(of course you need to do alot else, these are just the rough frame of your strategy)

Tip for pretender design/scales:
Go with enough astral so that with booster items you can cast wish/nexus. You can expand fast without an early SC so make it sleepy or imprissoned.
scales: dom 5+
high order
productivity, good if you can afford it, not vital by all means.
pick a heat or cold scale since income is not affected.
growth: I like growth, guess it's not vital however
misfortune: usually my pick with most nations
magic: I recommend getting +1 on research.