[Shovah32]

The Knights are nice sometimes, but you get a size 3 unit with only 1 attack for 100 gold, so they aren't great offensively.

My opinion on pretenders is pretty much the same as VedalkenBears - take a pretender with astral or a combat pretender.

Torin - Triton Kings are EA, not MA.

If you are fighting underwater, use shark attack. It is THE underwater spell.
Fighting above or under the waves, I suggest a combination of Mermidons(great troops, love them), Wave Warriors(cheaper than mermidons, quite tough, good offense) and Ichtysatyr Soldiers(poor morale, but tough).
Always buff your troops with your lovely nature and water magic(mass regeneration and relief are almost must-haves. Wooden Warriors/mass protection are nice and touch of madness and quickening both have their uses, although can tire your guys out).

Dormant W2E4S6 Dom6 Old Man of the Sea.
You get 120(well 128, 88 if you go W4) points to spend on scales.
Good astral magic means Golem access - your nation lacks the ability to summon SCs and golems can sort of help you spend your pearls.
You get enough earth magic to branch into earth quite well(Troll Kings Court+a pair of earth boots gives you E4, you can boost it to 5 with a ring of wizardry if you want) - a path which is very helpful, particularly for buffing your troops.

He can also fight quite nicely, with 100 health, great access to buffs(protection, reinvig, quickness, BoW, ethereal, luck, astral shield, resist magic) and 2 hand slots(and a few more) he can fight well.
He also has access to plenty of nice magic items, and on that note, a Golem with a skullcap and a crystal coin can become an very durable support caster, with will of the fates in particular being a great spell for them.

If you get earth via trollkings and astral with golems you can have:
Lucky, regenerating Mermidons with great MR(13+army of lead), 16 strength and an armour piercing trident(23AP damage for the win?), 25+protection and who recovers fatigue via relief(and friendly currents, also water ward under water gives them great defence).
Amphibious with great all round-stats and survivability, and with recuperation to convert those good stats into many, many stars of experience.