Runes for protection or warning?

For Ostara I intend to write down the things in my life that cause me pain and then ritually burn them as a way of releasing them. The ashes will be placed in a draw string bag and buried. Over that bag I want to place a stone and on that stone paint a warning to others not to open the bag or maybe a symbol to ward off intruders. I want my misfortunes to stay buried and I don't want someone to fall upon them and somehow release that onto themselves. I think doing this with Runes would be best. However, I am not as knowledgeable of their meanings as I would like to be just yet and I'm hoping someone might be able to tell which ones would work best. Thanks for your time and help. Blessed Be.