I decided to play again, this time on hard mode with maniac encounter rate.
I did most of witch wood, then cave of atlas, got all the levels I could from peak of ultai and with my chars thus quite high (Random 83, Sarah 88, Luciana 86 and Spark 92) I felt well equipped to deal with the peak of heroes. I breezed through it and after I chose my usual reward (Blessed Touch), the fairy told me "I should be going now... but your natural aura has persuaded me to give you more than I should... take your chances, heroes." And I could choose a second reward.
Anyone else ever had that happen?