Found a replicable/repeatable OOB using warp stone, above the rooftop camp toward yellow - clipped into skybox by hitting the usual 2 and warp stone straight up combo to increase height. No way back down either (other than repeating the same thing through the same gap with warp stone). Screenshots included to show the approx location (although this actually is easiest/pulled off most above the neutral central to screen, so a little bit further forward) and the effect (having travelled to a new spot afterwards, getting onto an inaccessible rooftop). 
