We datamined earlier that the Rank 5 and 6 Legendary upgrades do not currently require any currency for these upgrades, which includes Soul Ash.
Continue reading ยป
A new currency has been datamined on the Patch 9.1 PTR called "Mega Soul Ash", with the description of "Soul ash, but mega". Could this be a Legendary Catch-Up mechanism or a new upgrade material?