Casket of Souls

"I am Sallazar, spirit guardian of the kingdom of Amarillia. For two hundred years I was the keeper of an artefact of magical energy, so powerful that its creation took the lives of eleven grand wizards. It was a casket that could imprison a demon and was made to defend Amarillia in its darkest years.
When the demon came, I awoke ready to trap it with the cask. But I gambled and lost. Yet the demon can still be annihilated by the casket. There is a hidden spell that can open it and I can lead you to it. Please help for there is no other hope left to us!"
Hidden within the twelve magnificent paintings are twelve magical objects. Will you be the one to find them?