No spheres for me. The way it's setup it's not really a prison deck (unless falling into Null Rod/Crucible/Strip somehow). More of a very aggro deck with some disruption.
I've played it in a few tournaments and have sideboarded in the Newlamog several times but never cast it ... and I think the World Breaker has only worked once. But I like the feeling of having "an out" to almost anything ... but then again I might get rid of it.
The main reason for the ESG's was to be able to play out from under a Workshop's turn one sphere, which has worked several times. They will help with the World Breaker too though. For example Workshop player goes land, moxen, sphere or similar and I can go Ancient Tomb, discard ESG, Null Rod which can work out against Shops.