Assuming the feasibility of utilizing a brown dwarf for a gravity assisted slingshot, or Oberth Maneuver, what sort of hazards/difficulties could one expect during such a maneuver?
EDIT: To make this more plausible, would it make a difference if the brown dwarf were part of a binary system, and would thus have a slightly higher velocity (depending on its radius from its solar partner) for the passing ship to "borrow" some of it's velocity?
More specifically, if a fictional starship were to need a large boost in velocity to reach its destination (either due to low fuel reserves or somesuch scenario), and as I understand it, the closer to a celestial body that one can get, the faster the periapsis speed will be, what would be the likelihood of survivability of such a maneuver, in lieu of volatile storms, molten iron condensing in the atmosphere, lightning, x-ray bursts, etc.? Put another way, how limiting would those factors be to the success of the maneuver?
(Acknowledging of course, that diving too deep into its atmosphere would produce drag, and also assuming that the craft is protected by both an ablative shield as well as a superconducting magnetic shield, and also assuming that the ship has no other option available.)