I've played at least three beta games with opponents that had the Decalon ability (one being Pariden and the others being custom sovereigns). Not once was an Arcane Monolith placed on the map by the AI and I've scrutinized each huge map after casting Ineluctable Vision.
The Decalon AI players have gone from exploiting the spell (LH 1.8) to complete abstinence (LH 2.0).
So is anyone seeing LH 2.0 Arcane Monoliths?