Acid Throne
Wondrous item, very rare
This large throne is carved from a block of magically frozen acid.
A character sitting on the throne takes 2d6 acid damage each round.
While sitting on the throne, all of a character’s attacks, spells or other actions and effects which cause acid damage automatically deal maximum acid damage.
If the throne takes a total of 20 or more points of fire damage during a single round, the frozen acid instantly melts and the throne is destroyed, bursting into a massive wave of acid which causes 12d6 of acid damage to everything in a 30 foot radius.