what is a magma stone used for
The Magma Stone is a drop from the Lava Bats, Hellbats and Bone Serpents (?) found in The Underworld. It causes your melee attacks to inflict the On Fire! debuff on enemies, and also gives a red flame particle effect whenever you swing a weapon. The Magma Stone is very deadly when combined with Frost Armor and any energy beam sword like True Excalibur due to being able to inflict both Frostburn and On Fire! Debuffs, increasing the damage over time. 2  The Magma Stone can be obtained before Hardmode.