Geoff Johns 3 Legion story has been something that he’s been talking about vaguely for quite a while. Since the current Action Comics Legion story was first being talked about. I had always just assumed that it would be an Action Comics story, but that assumption was destroyed yesterday when Final Crisis: Legion of 3 Worlds was announced.
I can hear the groans from here. Why is DC having one mini-series tie-in to another? Honestly, that is just the way things are. A company has an event, there are going to be extra books that tie-in to it. This is not something unique to DC. If it was, then you would not have had Civil War: Frontline, World War Hulk: X-Men, etc. Tie-ins are not necessarily a bad thing, so long as they remain only tie-ins. It is when a tie-in becomes an essential part of the story that there is trouble.
A tie-in should be supplemental to the main st experience, Marvel has done a decent job with this. DC, not so much. In the lead up to Infinite Crisis, DC had 4 mini-series going on. ory. From myOnce Infinite Crisis started, each of the minis had one special. These specials turned out to be necessary parts to fully understand Infinite Crisis, especially the Villains United special. DC appeared to have learned their lesson with the 52 tie-in, World War 3. While this event was a tie-in, and represented in 52, you did not need to read one in order to read the other. Unfortunately, DC showed they had not learned anything with the Countdown family of titles. But that is for another entry.
Too make a long story short, (too late) there is a way to write a successful tie-in, even if it is going to be a big event on its own. From interviews that I have read with Grant Morrison about Final Crisis, and Geoff Johns about Legion of 3 Worlds, it seems that they understand how to be successful. Grant has said that you do not need to read anything else, to understand Final Crisis. Geoff has said that while there is a launching point within Final Crisis, you do not need to read it to read his Legion story, and vice versa. So long as they stick to this plan, then things should go well.