Amulet of the Grammarian

An Amulet in the shape of a magnifying glass. Once the user put it on his neck, the amulet seems to shine pale yellow. The Amulet of the Grammarian can be used, once per day, to alter one letter in a spell title, as you're casting it, for a different effect. For instance, the wearer can start casting Cause fear and activate the ring to instead cast Cause Bear.

The charges increase with each of the spellcaster's level. (increased by 1 every 2 levels with the maximum of 5)

Notes: The number of charges increases by 1 every 2 levels