Spell Tomes (DLC4) is the fourth official plug-in for The Elder Scrolls IV: Oblivion. Created by Bethesda Softworks, the plug-in was released on September 1, 2006, and takes up 2.4 MB of hard-drive space. The plug-in features hundreds of new spell-giving books, ranging from high to low levels. These new spells exceed the maximum magnitude of Oblivion's vanilla spells, however, this plug-in aims to balance slightly detrimental effects with a lower Magicka cost. The added tomes are located in dungeons as loot.