Place this clip right after the threat appears in your edit, opening with the enemy spotted alert to set up the danger, then following it with the Roblox oof for the aftermath when your character goes down.
About this sound
This is a short human voice clip of a drawn-out ahhh scream, lasting under two seconds, pitched like a startled game unit reacting in panic. It feels funny and frantic rather than scary, turning a small fright into an over-the-top reaction. The clip comes from the Warcraft games, using a human character voice.