Particle cannon (Tal'darim)

A Particle Cannon are Protoss cannons used by the Tal'Darim to shoot down enemy air targets.

Evil Awoken
In the Whispers of Oblivion prologue campaign third mission Evil Awoken, you command Zeratul inside the Temple of Erris on planet Atrias. Once your inside the Temple, you get a bonus objective to destroy the 3 Particle Cannons. Each time you destroy one, you get reinforcements from Praetor Talis.