Easily the most complicated addition to the streamlined paths system as of yet, but Christ is it worth the complexity. Rather than making a number of new novice paths like they did for the priest and the warrior, and with no existing class-central customization like the rogue, when the time came to expand the magician, they made it modular. Whenever you gain a new feature from the magician class, you can replace it with a number of options depending on what traditions you know at the time.

Want more castings of level 0 spells? Replace cantrip with the Arcana option. Don't plan on using sense magic, but want to get a burst of speed to charge your enemies at the start of combat? With Battle, you can make that choice. Want to be a master at avoiding damage? If you have the Soul tradition, you can give up counterspell to enhance the effects of damage-avoiding challenge rolls. Want all three of these for some reason? Sure, just have discovered the Arcana and Battle traditions by level 1, and the Soul tradition by level 5.

10/10 would trade soul for again.