Well I don't know why, but Black Arks are kind of useless at the moment!
They have bad auto-resolve points (they have WAY to many casualties), their Dread Expansion stance doesn't give themself replenishment and I would like to see a constant replenishment effect for them as well as heavy sacking bonus. Else you're mostly better off just use them as single unit for the circle buff and some bombardments (that take way too long to cast btw....)

Man, I would love to see them able to embark on land, maybe with attrition damage. Give them the "water filled" ability from Repanse while they are on sea, when they embark on land they are able to walk 2 turns without taking attrition, then they need to go back to the ocean... that would make them finally a real game mechanic for the edgy elves!

What do you think ?