[Idea]More Interesting Magic Victory
Magic victory right now is just a generic civilization or wonder win. It really is what you do if your winning but can't be bothered to try and conquer the other players. All you do is get a certain amount of tech and then wait to build a bunch of buildings, and then cast a spell which is just even more waiting. That's really really boring. Magic victory should be spiced up and made much more competitive and riveting.
To do this I would suggest adding a global non-additive resource called Shard Mastery. Instead of requiring one of each type of shard the Spell of Mastery would require the casting player to have the most Shard Mastery output of all the players. Shard Mastery would be granted by shards and various magical buildings, like the Forge of the Overlord towers. Upgraded shards would also grant more Shard Mastery. The Forge towers would be made world achievements and scattered among the magic tech tree. Thus players going for a magic victory would have to plan it from the start and compete amongst each other to amass the most shards, magic tech, and unique buildings. This would be much more organic and interesting then the current system. Like military conquest it would be organic, challenging, exciting, and require planning.
The current Spell of Mastery system is very dull and seems to exist only so players have a I'm done button when they reach a certain tech and don't want to play anymore. Making the Spell of Mastery more competitive and strategic would really help liven up the end game.