From WoWWiki

Crystalforges are used to create unstable flasks in Blade's Edge Mountains.

There are two crystalforges, the Bash'ir Crystalforge and the Fel Crystalforge.

Bash'ir Crystalforge

• Location: Bash'ir Landing (55,11)
• Can be used to create: [Unstable Flask of the Sorcerer]

Fel Crystalforge

• Locations: Forge Camp: Wrath (32,40) and Forge Camp: Terror (29,81), Look for Green Bubbles
• Can be used to create: [Unstable Flask of the Beast]

Each flask costs 10 [Apexis Shard] to make, but can be made in lots of 5 as well (costing 50 shards).

There are other unstable flasks available but these must be bought from Aether-tech Assistant during the Bash'ir Landing Raid event.