Upcoming in 1.5 is a new system of advancement for post-50 characters.
As you “attune” to one element, you unlock abilities to help fight beings of that plane.
It starts by allowing you to bring out a regular rift of the plane you chose with a specific lure, giving you greater dps against beings of that plane, and giving you better resistance against that element. The lure just opens normal rifts, but hey, no more hunting for an invasion if you need an air rift for the Water Saga, or a death rift in Freemarch, just get a friend to open the right type for you!
Depending on the abilities you unlock, you will receive greater spellpower or attack power while wielding a specific weapons, a fluff ability, and a small boost to a particular stat.
More information in this great overview at Zam that links to more specific charts for each class after the overview.
My first impression is to wonder why secondary stats receive a boost from some elements, rather than it being primary stat or endurance only for that class. Such as Clerics receiving INT bonus from Death and Fire, same as Mages. These are supposed to be s very minor boost, but of course the min-max is going to go Death or Fire as a Mage, and Cleric Tanks will end up gently nudged to attune to Life, where Warrior and Rogue Tanks will be nudged to attune to Earth.
Weapon choices for boosts to spellpower and attack power seem odd, especially for clerics and warriors. Some choices are for weapons that don’t really exist in the game yet, such as for a two-handed axe or a polearm. The increased endurance of Earth for Clerics is paired with a bonus to Staff or Wand, not that useful for a tank. (Unless by “wielding” they mean “equipped” and you can only choose to add points into one weapon type, not both. That wasn’t clear from the guide. If that’s the case the bonus to wand would be chosen by Cleric Earth tanks and give an equal increase to the bonus to mace available to Cleric Life tanks.)
Hopefully they’ll work out the details a little better, and keep the power creep to a minimum when they bring out the second and third tier of this system.
I’m hoping for some visual fluff in later honeycombs, like a soft glowy aura (like the low-graphics version of the Gem of Boundless Energy, which is just an oval glow around you) or eyes, or weapons. I think that would be really cool to see on the field of battle.