Mark of Ironwood

The spell itself offers a very simple use. It enhances density of anything it is placed on DRASTICALLY, making simple objects very difficult to destroy with brute force. I once observed an experiment where a Mage cast a High-powered version of the spell on a window, and offered whoever could break it with brute force two gold coins. No one managed to break it, apart from a very, very big Ogre. That says something, really.. Anyhow, the spell itself works by drawing energy from latent ley-lines, or until the energy you put into the spell runs out.

Effect

Come on, even an Ogre would be able to make this one out. The spell is designed to protect most common day objects. Everything from a door, to a table. Hell, you can even write the spell on a shield, boosting it's defensive capabilities. As of right now, several of the tables in Tol Barad has gotten this mark.. Some people are very wild when they get drunk....

Source

The spell is very rare, and this copy is one of the few surviving I've managed to collect.

At the bottom of the page is a small mark. The mark looks like a Circle, with Two snakes coiling around a branch