Originally Posted by
GDB
Main stats are still dependent on the piece, not the set.
Flower - flat HP
Feather - flat Attack
Timepiece/Sands - can be any of Attack %, Defense %, Elemental Mastery, Energy Recharge, or HP %
Goblet - Attack %, Elemental Mastery, Elemental % (individual elements, not as a whole), or Physical %
Helmet - Attack %, Defense %, HP %, Elemental Mastery, Crit Rate, or Crit Damage
Instanced bosses like Childe, Dvalin, and domains don't scale with world level though. World level is for the outside world, like the big Wolf boss or random enemies around the world.