御札 Kotodama written on them by a magic user. They're used to store a spell for use by anyone (magic user or not) or to apply it for longer and more powerful effects. The creator, shrine, or temple often stamps the talisman with their seal in red ink to mark it as official. Most any substance that can be used to write with or written on can be used. But the farther the supplies are from high-quality stick ink and bamboo or cotton paper, the harder it is and the more ki is required. Ofuda protection talismans (kind of like a blessing) can be purchased at most shrines and temples. Tradition says, that they last a year and should be returned (to be burned) and replaced. In Onmyoudou and Ofuda: A Research Compendium, Tsuchimikado Yukitada stated that he felt keeping things simple and straightforward was best. So he would use at most 2 words on his ofuda. The ki could be easily directed into the paper or other medium for the strongest effect of the spell. While some practitioners preferred to use ancient symbols for their talismans, Tsuchimikado felt that a fluid script fit the flow of ki better.