Voting against. It would be some nice flavour, but there's only one level where it's possible. And the amount of graves there is massive. So basically this would have a chance to turn one already tricky level (especially with ants opening the walls) into living hell. If graves were scattered around the dungeons, then, sure, maybe... But as-is it would mostly seem like another gremlinbombed water cave, with added deadliness flavour.