I'm following five korean web comics (others being Tower of God, Noblesse, Layers, and Chess Isle), and 3/5 of them have very slow-moving stories. I think it's clear that Eldermask and En have their goals in Magician, but it just seems to take a really long time for anything to happen. Perhaps a better word here is that the story isn't focused -- there are several plot threads but each is crawling towards resolution.

I think Eldermask is searching for information about immortality for a more personal reason that hasn't been introduced to us yet. He was surprised when he was told that the other immortal looks exactly like him, so I don't think Eldermask is targeting him.

I'm actually more interested in seeing development of Iremi's magical abilities, or some sort of structure / explanation of how spells work in their world. So far we've seen that magicians have a certain affinity, such as fire, lightning, or nature, but hardly anything in terms of spell acquisition, casting costs, spell possibilities, etc.