Complex sentence: When the gig ends, David meets said Jamaican guy, who goes by the name Robert Marley, who despite David's skepticism, appears to not only able to do strange tricks, but also knows about David's past and possible future.
Split into simpler sentences: When the gig ends, David meets said Jamaican guy, who goes by the name Robert Marley. During their short meeting, and despite David's initial skepticism, Marley shows he not only can do strange tricks, but he also appears to know about David's past and possible future.