@macroblitz
(1) He abandoned his tower
(2) He's the most powerful wizard
(3) To absorb his power that was left on his tower
(4) Anastasius answered it himself, if he comes there and go straight for an attack, people will see it as a treason and there will be more chaos to manage, the best option is to come and swoop in as a hero when the Kingdom was thrown in chaos after losing their King.
(5) I don't know whats Lucas supposed to do on this case ? He already figured that someone is using a stealth attack because the royal wizards said that there is no trace of magic but he sensed differently. How is he worthless if he managed to stabilizes the King ?
(6) Athanasia was as clueless as Jeannate because adult around them didn't tell them anything, reading many book doesn't mean she'll have the skils to figure out everything just by thinking about it
Its called plot.