The Encyclopedia Frobizzica
Fireproof
From Zork II (In-Game Description):
A strange little man in a long cloak appears suddenly in the room. He is wearing a high pointed hat embroidered with astrological signs. He has a long, stringy, and unkempt beard. The Wizard draws forth his wand and waves it in your direction. It begins to glow with a faint blue glow. The Wizard, in a deep and resonant voice, speaks the word "Fireproof!" He cackles gleefully.
The dragon tires of this game. With an almost bored yawn, he opens his mouth and blasts you with a great gout of fire, but it washes over you harmlessly.