Trion has released a preview of one of the new ascended souls available in the upcoming 3.6 update. The new Frostkeeper soul is a new healing class with a very specific focus — keeping us tanks alive. In addition to general healing, this ascended Mage soul can protect its allies by creating barriers around them. They can also channel a special ability into an ally that protects them from death.
The soul also apparently works well with Cholomancer for massive heals.
As with other soul introductions, a large chunk of Trion’s preview for the Frostkeeper is lore-ific. You can read all about the origin of this soul on the Rift blog.