Is there a strategy involved using the cards that have lower power and blocker? For example, what's the use of Seamine, King Coral, and that other dark one? Has anyone used them in their deck?

The only reason they can be considered useful at all is because they are blockers that can attack players normally. They have great versitility but at the price of being so expensive that they are pretty much unplayable.

I definately wouldn't use them in a Contructed deck but they seem to be more useful in a draft situation when versitility like that is really needed.

I've never played draft, so I didn't think about it's versatility there. Still, it is a lot of mana to pay for such an oddly made creature.

its the first set, of course its going to be like. they are just introducing the game, and having those types of creatures is a very unbalancing thing with the card choice we have. So they balanced htem out with high cost. As we go on tho, we will get bigger and better blockers that can attack.

Power doesn't matter much with regard to the Water Civ -- a 1000 Power critter can break a shield just as easily as a 9000 Power critter. Sure, the smaller critter can be stopped by most blockers -- but Water Civ decks shouldn't be allowing Blockers (or any other type of opposing critter) stay on the board very long -- BOING!).