Crystallized Fel will add 3 ilvl to your Legendary Ring to a maximum ilvl 795. Crystallized Fel which you acquired from killing Archimonde can now be purchased for 1250 
Valor from Dawn-Seeker Krisek.
There doesnt seem to be a cap on the amount you wish to purchase, but there is a cap on how many Valor points you can carry.
1x Crystallized Fel will add 3 ilvl to your Legendary Ring to a maximum ilvl 795.
This is great news for myself and hope this is helpful to you too.
