Ras Nsi is an evil warlord who waged war on Chult centuries ago.
There are hordes of undead bearing his symbol, that of a blue triangle, on their foreheads.  Yashida, one of Ras Nsi's underlings, stole the apocalypse dagger from Viari during a dinosaur race.  The oracle at Orolunga told the waffle crew that Ras Nsi was suffering from the death curse, and that the group should try to kill him.  Ras Nsi appeared in the temple of Dendar, but before he could do anything, Miranda knocked him back into the teleport circle and he vanished.