During game play hold L and R and enter the following cheats:
All Levels:
Right, Right, Left, Left, Up, Down, Up, Down
Damage times 100:
Up, Down, Up, Down, Left, Right, Left, Right

Enemy attacks pass through Bard:
Left, Right, Left, Right, Up, Down, Up, Down

Full health and mana:
Left, Left, Right, Right, Up, Down, Up, Down
Silver pieces and Adderstones:
Up, Up, Down, Down, Left, Right, Left, Right
God mode:
Right, Left, Right, Left, Up, Down, Up, Down