From Diablo Wiki
Nephalem Glory is the buff applied from a Nephalem Globe. It applies a plus to speed and increases damage and the rate at which health regenerates.
Running over subsequent globes will increase the potency.
There are three levels of potency. Basic which applies the above buffs, the second level applies the buffs plus adds lightning that arcs between enemies every time a target is hit. The third level causes columns of lighting to fall down on the target and spread out.