A Clear Sphere is used when you've completly completed the grid(like it will ever happen) when you have no more empty nodes left you can use this say on a strength +1 then use a strength sphere which will turn it into a strength +4 its only to allow you people to advance more by clearing things they dont use or things that are worse than what you can replace them with!!
NOTE: WHEN YOU CLEAR IT IT WILL EFFECT ALL CHARACTERS WHO HAVE ACTIVATED THAT SPHERE
EG.. IF YOU CLEAR THE STEAL NODE THEN NONE OF YOUR CHARACTERS WILL BE ABLE TO STEAL!!!!!
TSA