http://prntscr.com/drdcr7
i put a background and region at the same size and place and it generates this substance
http://prntscr.com/drdi75
this cannot be eliminated with lamps anyway
it also happens when multiple backgrounds were place at the same spot
http://prntscr.com/drdl0d
no region on it though
P.S i think this is related to the real slayer's http://www.plazmaburst2.com/forum/viewtopic.php?f=122&t=15429&p=144164#p144128