Hizzinra was a Mahjarrat killed on Freneskae. They were part of a group who stopped to rest for the night, only to wake up and find what they had presumed to be stable ground had broken apart, and that they were now floating uncontrollably through the lava. Hizzinra prayed for salvation, but ended up being killed by a wave of lava. Their deathstone can be found after the lavafall on Freneskae, during and after the Children of Mah quest.
Finding their deathstone, alongside the other three, is a requirement for the master quest cape.