Kouen is so badass, pulling out a pillar of earth to absorb magoi from the resulting magma? And the smile he has the whole time, even thousands of those black Djinns wouldn't be able to hurt him. These types of strategies can only be pulled of with multiple vessel holders or someone with multiple Djinns, wonder if Sindbad has similar strategies?
Astaroth is a flame Djinn, and its Djinn equip evaporates blood (or whatever the Black Djinns have) and as a result they explode? Agares seems to be using strength magic?
When Koumei's magic said "Big Dipper", the first thing I thought of was Fist of the North Star and maybe he'd use Hokuto Shinken.
Dantalion seems to be using strength magic as well, his extreme magic is maybe a large scale transfer circle. Even with his normal abilities, he's capable of transferring the Kou army to other places instantly, which is pretty scary. I wonder how far he can teleport one thing.
That medium is capable of producing ten thousand black Djinns, and if it is just an introduction to the last enemy as people have been speculating, how big will the medium be in the last arc? Maybe every metal vessel user must contribute in defeating it and not just 6 here.