Lava Effects

Lava or magma deals a minimum of 2d6 fire damage per round of exposure, while cases of total immersion (such as when a character falls into the crater of an active volcano) deal upward of 20d6 fire damage per round. The exact damage is left to the GM’s discretion, based on situational terrain elements.

Damage from lava continues for 1d3 rounds after exposure ceases, but this additional damage is only half of that dealt during actual contact (that is, 1d6 or 10d6 per round). Immunity or resistance to fire serves as an immunity or resistance to lava or magma. A creature immune or resistant to fire might still drown if completely immersed in lava (see Suffocation and Drowning on page 404).