Tashani  

Tash is an unresistable spell that lowers the magic resistance of the target. In this version, it lowers it 20-23 points, making every spell that is magic-based (as opposed to, say, fire-based) land a little more easily.

Enchanters do this to help themselves, and others, land their spells. As a prelude to a magic-based slow, a tash is a great appetizer, making it more likely the slow wil land on the first try.

Tash is actually a form of poison, though, and can be cured. The indicator that says this increases poison counter by 1 says that any poison cure spell (including the very low level cure poison) that removes at least 1 counter of poison, will cure this.

This is useful to know when a mob casts this on you -- ask a healer (even rangers can suffice) to cure poison on you and this will raise your magic resistance back up to what it was pre-Tash.