You had read a book about a ritual to summon a demon.

You were in your house, in the living room with a huge circle on the floor. You were ready to do the ritual. You started and when you least expected it, you began to feel the presence of something strong and macabre when you opened your eyes and saw the demon. It had big black wings, black eyes with red irises and was so tall that it almost hit the ceiling, apart from its clothes all torn with blood and its long horns.