Single black dragon - how far can you get?

[Metathron]

Just a quick question off the top of my head: In the battle against Samman, for example, how do you protect the dragon from being destroyed by the archdemons when they act right after your dragons? I can imagine moving the dragon to a hex that has only two adjoining hexes and casting demon portal on both, but is there such a spot in this battle? If there are three, what would you do to occupy the third hex? The dragon's wall is the only thing that comes to mind.

Anyhow, muy impressivo!