WoW Heirlooms — Browse All Heirlooms
Track your World of Warcraft heirloom collection. Browse all 134 heirlooms with vendor locations, costs, and upgrade levels. Filter by armor slot and weapon type.
Browse all WoW heirlooms with upgrade levels and acquisition sources. Find heirlooms from vendors, achievements, and special events. Track which heirlooms you own and their upgrade status via Battle.net.
Mystical Kilt of Elements
Source: Vendor: Goram.
The 
Mystical Kilt of Elements is a Cataclysm-era heirloom leg piece unlocked through the Guild achievement system, becoming available for purchase once your guild reaches the required level.
Reach Guild Level Requirement
The Mystical Kilt of Elements becomes available for purchase through your guild vendor once your guild has unlocked the appropriate guild achievement. Heirloom leg pieces like this one were confirmed to become available via the guild achievement system starting with Mists of Pandaria.
Purchase From Guild Vendor
Once your guild has unlocked the legs achievement, visit your guild vendor and purchase the Mystical Kilt of Elements. Some players have reported not seeing it on the vendor list despite meeting requirements, so check that your character class is eligible for this mail-armor leg piece.
Tips
You can enhance the Mystical Kilt of Elements with leg armor such as
Icescale Leg Armor or spellthreads like 
Runic Spellthread, and they will scale down with your level.