The way I use it: Click "Use Artifact" button if you have a charge, then click anywhere on the map you want to spawn the Space Monster. You will only see it (I think) if you spawn it in any of your areas of influence. Beware though, if you do that it will attack your stuff along with everyone else's. I have been spawning it in planet clusters of my most threatening opponents. You won't be able to see it unless you have vision there, but trust me, its there. I spawned one recently in enemy territory, then used the "Dimensional Mirror" artifact to reveal an area of the map where it spawned. It was there reeking havoc on the enemy as advertised 
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