How do I transform an object into a monster?

[FlawlessHappiness]

Make it so it is not the player that collides with the script area, but rather the item.
Place a squared script area in the middle of the corridor. (I guess it is a corridor)
Then put some diagonal block boxes so the item, is forced to hit the script area.

so the script:

void OnStart()
{

AddEntityCollideCallback("ITEM", "ScriptArea_1", "OnItemCollide_1", true, 1);
}

void OnItemCollide_1(string &in asParent, string &in asChild, int alState)
{
SetEntityActive("servant_grunt_1", true);
SetEntityActive("ITEM", false);

}