We've covered common spells, we've covered insta-spells.
More powerful yet, and ones that I've only thought about in theoretical terms and not even tried to create yet, and Archetype Spells.
These would take a team and probably decades to put in place. These are the type of spells taught in Harry Potter - do a hand motion JUST SO while saying a word or two JUST SO.
My theory is that doing this takes the insta-spell set up, plugs it into a superior source of power, and makes it so anyone can pull the trigger. One person or a group can create it and get it to the insta-spell stage. From there the rest of the group works on it, maybe daily, certainly at least at certain times of the month, to make it universal. All using the same Otherworld set up, all using the same gesture and words. Maybe it has to be taught by 'apostolic succession' - those who created it taught others, who then taught others. Could the apostolic succession take place in dreams? Sure, why not - plenty of sacred stories show that happening. It's a way that can't be relied on, but WOULD explain the re-discovery of types of magic long lost that are being recovered. Ivo Dominguez, Jr, talks about inspiration he's gotten that sounds much like that in his book "Castings: Creating Sacred Space" - recently released by Weiser books! Yay Ivo! Yay Ankhie (the Weiser logo is an Ankh).
Ultimately I suppose that the spell would move from servitor to egregor ....
Of course I'd like to see these type of spells being done again. Will it happen in the next astrological age? Dunno. I'm quite sure I won't be creating any this life time!