I often run into opponents trying to Go To Ground in Area Terrain near a Ruin, arguing that their unit is 25% obscured by the Ruin and thus get a 4+ and since they are in Area Terrain and get a 2+ bonus to cover for a total of a 2+ save. This seems like trying to have your cake and eat it too. Are these people stuck in 5th edition??? The rules clearly state on page 91 of the BRB:
"Area terrain is always difficult terrain. Models in area terrain receive a 5+ cover save, regardless of whether or not they 25% obscured. Models that Go to Ground in area terrain receive +2 to their cover save, rather than +1."
So you disregard the 25% obscurement from the Ruins, apply your 5+ from Area Terrain, with your 2+ bonus and get a 3+ total. 2+ cover can only be achieved with a USR like Stealth or a Camo Cloak.
Most importantly, cover is on a model by model basis and models that are not in the Area Terrain, regardless of if the majority of the models are in it, can be focus fired and do not receive a cover save (especially if they are the closest models, in which case they don't even need to be focus fired).
I need a list of page numbers to quickly read off because this happens almost every game I play. Any help is appreciated.