If you collect all the balls of helbreath, you can make a wish to the GameMaster.
The wishes you can do are for example:
1000 more of reputation, one Kloness item +3, Giant Battle Hammer+3, Berserk Wand (MS20) +3, a Horse, any primary drop item with stats +15 (example: crit 1, PA 33 PlateMail(M) + 15). Sharp BBH HP 77 +15, Necklace Of Xelima, Necklace Of Kloness, Magical BBH+3, etc.
Green Ball is second drop of spectre.
Blue ball is second drop of Asgarde Giant.
Red ball is second drop of demon gargoyle.
Yellow ball is second drop of Ettin.
Dark Ball is second drop of Nazgul.
All the balls are very rare drop.