Place it just before your army engages, after a teleport sound marks the warp-in and before a wtf boom lands on the impact moment, so the sequence builds from arrival to charge to explosion in your StarCraft edits.
About this sound
This is a 1.2-second voice clip of a Protoss Zealot from StarCraft saying 'Gau'gurah' in a deep, processed alien voice. It feels fierce and battle-ready, like a charge order delivered right before combat starts. The line comes from the Zealot unit in StarCraft Remastered.