The light emitted by these insects that live in the dungeons attracts not only dangerous predators, but also mechanical monsters lost in the intricate passages. If you let the Firefly, it will immediately lure to battle one boss: Mechanical monster, an Ancient horror, an Underground hunter, Queen Of Goudov and Lord of Goudou. 

You can only defeat the summoned monster alone. It is recommended to have level 11 and older.  If you win, you will receive all trophies, even if the boss is much younger than you in level. Points in the rating "Triumph"  for killing the summoned boss not credited. Get ready! After releasing the firefly, you immediately get into battle.

The item can only exist in Elinor's world 30 d., after which it will disappear without a trace.