The Heroic Quest of the Valiant Prince Ivandoe S04 E03 The Prince and the Chosen One

Bert becomes the chosen one as leader of the council of heroes after lifting their sword, with Henry the Hedgehog retired being leader. Because of being squire for Sir Bertbut (which is Bert), Ivandoe learns that the heroes were talking about the "Epic Griffin of Doom", making him had to fight it.