The Hangout thread.Zaratras disappeared because he had accomplished what he had to do. I think Elaine's wish was to stay with Ban or something. That makes things more complicated.
It's not quite that simple if I'm not mistaken.
The different souls returned to their bodies because they had lingering regrets.
Elaine regretted that she couldn't spend more time with Ban but once she realized that he has people who care for him and that he isn't alone and that Ban isn't interested in Jericho (romantically), how she thought, she could eventually move on and just continue waiting for him to bring her back.
Zaratras' biggest regret was that he sent Dreyfus and Hendy to Danafor and that he couldn't help them with Fraudrin (remember, the dead can literally watch the living in Nanatsuverse) and once he was able to rescue his brother and Fraudrin was seemingly killed that issue was solved in his eyes. Fraudrin was still alive, of course, but that didn't matter once Zaratras already accepted that he has to move on.
Merascylla's spell didn't work in the sense that the dead got "tasks" they have to fulfill before they can leave again. She just pulled them back from purgatory/the capital of the dead (I guess purgatory is demon-only) and they tried to return to their bodies.
People like to overlook that the majority of those souls didn't even stick around long at all. The people whose bodies already decomposed couldn't return to the world of the living at all and were stuck as souls. Those who just died became these zombie-like monsters who roamed Britannia for a short while and only the likes of Elaine and Zaratras got to stay for a longer time because their bodies were preserved (Zara is a druid, I bet they did some fancy shit with him or he restored himself. And Elaine is obvious)
I also think the whole "magic is dispelled when its caster dies" thing doesn't apply because Mera's spell was a one-time-activation thing. She opened the gate and lead the dead back. It's not like she actually BOUND them to the world of the living. She agitated them a bit but they all acted on their own accord, even Elaine when she attacked Jericho and Ban. I think stuff like that and say Critical Over just need magic (power) to get activated once but they don't work like stuff like Merlin's Perfect Cube or the ice thing where she casts a spell and has to keep it up (with Infinity).
