RuneScape Classic Wiki
RuneScape Classic Wiki
The main RuneScape Wiki has an article on: Wizard's Mind Bomb
The Old School RuneScape Wiki also has an article on Wizard's Mind Bomb.

A Wizard's Mind Bomb is a drink that can be purchased from the Barmaids in the Rising Sun Inn in Falador for two gold coins. When consumed, it will temporarily raise your Magic level by 2 (if under level 50) or 3 (if 50 or over) levels and restore 1 hitpoint, but will reduce your attack, strength, and defense by at least 2 levels. Since there are no magic potions in RuneScape Classic, the Wizard's Mind Bomb is often used by players using magic in PvP.

One Wizard's Mind Bomb is needed in the Dragon Slayer quest to open a door in Dwarven Mine.