Which magic schools should I choose for the late game? Or should I go for a specific artifact?

I think mages don't have any problems with knowledge anyway... So, in my opinion, Chaos and Summoning are better choices than Nur for the late game, when mana is already over 300, because the path to Chaos Archmage involves taking unnecessary abilities (why do mages need machines? Except for the Hafiz, but the path to Chaos Archmage implies giving up Ballista). Therefore, I would choose Chaos and Summoning (Summoning is always relevant, and there is a counterspell against dark opponents).