During the game press [Ctrl][Shift][~] and type in (include the SPACE):

 @ bythepowerofgrayskull                Full heal
 @ ihavethepower                        Full mana
 @ yourbulletscannotharmme              The wizard is invincible
 @ dontfearthereaper                    Adds souls
 @ castratetheheahens                   Wizard can collect red spirits
 @ timeisonmyside                       Resets the spell timers
 @ aplethoraof (monster name)           Summon 4 (monster name)
 @ alliwantforxmasisa (monster name)    Summon 1 (monster name)
 @ gimmegimmegimme (spell name)         Give (spell name)
 @ ragebuilding                         Levels you to level 9 and gives you all spells
                                        and creatures (local multiplayer)