A hotfix has gone live a couple hours ago on live servers, making Storm Sigil drop from Forbidden Reach rares! This makes Storm Sigils much more farmable and smooths out some of the RNG out of the gear catch-up in the Forbidden Reach. From limited testing, it seems that all Forbidden Reach rares have around 50% chance to drop Storm Sigils. It is worth noting that as Storm Sigils are a currency, they are NOT account-wide.
Forbidden Reach Catch-Up GearThe addition of Storm Sigil to Forbidden Reach makes catch-up a lot easier for alts, as you no longer have to pray for ilvl 385 tokens of the specific armor type and slot to drop. You're able to purchase ilvl 359 Primal Storms gear from Mythressa in the Forbidden Reach for small amounts of Elemental Overflow, and these pieces can be upgraded with Storm Sigils to ilvl 385 (and then further upgraded to ilvl 395 with Untapped Forbidden Knowledge):
Gear SlotUpgrade CostCloaks, Off-Hands, Shields, Belts, Bracers5 Storm SigilBoots, Gloves, Agility/Strength 1H Weapons, Shoulders7 Storm SigilIntellect 1H Weapons9 Storm SigilChests, Helms, Pants0 Storm SigilAll 2H Weapons, Ranged Weapons4 Storm SigilIt is worth noting that necklaces, rings and trinkets do not have ilvl359 versions.
Read more on wowhead.com