This item can be purchased for 35 from in Blade's Edge Mountains.
Using this item on the gates at Bash'ir Landing spawns an elite mob that can be beaten by a moderate-size party. Their loot tables include Apexis Crystals. When you use the Accelerator Module to summon the elite is will be consumed. It is best to collect a few Accelerator Modules to ensure you can summon a few if you die.