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Wall of Magma (Sp): Once per day, an x or older ruby dragon can create a wall of cooling magma. This functions as a wall of stone spell, except one side of the wall (selected by the dragon) sends forth waves of heat, dealing 2d4 points of fire damage to creatures within 10 feet and 1d4 points of fire damage to those past 10 feet but within 20 feet. The wall deals this damage when it appears and on the dragon's turn each round to all creatures in the area. In addition, the wall deals 2d6 points of fire damage +1 point of fire damage per caster level (maximum +20) to any creature passing through it. The wall deals double damage to undead creatures. This is the equivalent of a 6th-level spell.