|The key to this fight is to understand one thing and be patient and cautious. When Bobby gets hit a lot, he pulls out his shield, and then anything that hits his shield gets reflected into a large pile of extremely lethal blobs that bounce all around the room. The shield protects him from all sides, not just the front (for some reason). So never inundate him with lots of shots. Always use just a few shots at a time, then take a break. That will make him launch as few shield-blobs as possible. When you see that shield come up, hold your fire! This of course also means no summoning golems, no Energy Barrage, and definitely no Armageddon!|
Also, stay away from him to avoid the extremely deadly spin move, and just remain very cautious and defensive in general. All of his hits do a lot of damage, so you're better off carefully avoiding the hits rather than trying to beat him as quickly as possible. If shield-blobs are already in flight, don't attack him again until they have gone away. That will mean a lot less stuff to dodge at once. Steelskin can help a lot, and you should try to conserve enough magic to cast Life. That will basically give you a double-length life meter, if you time it well. It's not really worth it to cast attack spells on him. Save the magic for protecting yourself, and pelt him with fireballs when it's safe.
Lastly, if you just can't win, go gain some levels or upgrade your equipment! Look at your Fairy selection carefully too. Some are a very bad idea, others can be very useful.