The new system replacing titan forging to offer some creative gear without the ever inflating item levels seems to be now live as of today's PTR deployment.
It offers a varied amount of Corruption in a numeric value and the benefits are varied as well, critical strikes, haste, mastery, healing received, leech, avoidance percentages. Also has some unique benefits like 40% of health regeneration continues while in combat and this one which is your spells and abilities have a chance to grant you a flash of clarity, reducing the cooldown of your next 3 spells cast by 2 sec.
The Corruption will tally up to give you side effects of up to 4 currently and the magnitude of them is directly linked to how much gear you wear with Corruption and how much your total corruption equals.
Item Comparison: - https://ibb.co/P63F25g
Corruption UI: https://ibb.co/phTdDtm
Side effects: Grasping Tendrils, Grand Delusions, Corrupted Zone, Creeping Death
Equipment slots currently affected by this based off recent PTR testing is rings, gloves, feet, legs, weapons & belt so far.
New essences seem to reduce your corruption if you use them in a minor slot of which there are now 1 Major & 3 minor in 8.3.
Token of Death's Door Essence.
Recent datamining does suggest the corruption on the items can be cleansed eventually.
Imgur backup images: https://ajlowe32.imgur.com/all