The Mutant Rancor you will say! Gues what? NO!!!
Do this just for fun!
In a table with big open spaces. Put yourself invisible (notarget). Spawn a mutant rancor (npc spawn mutant_rancor). If there are no other NPC or vehicles it will remain inmovile. Spawn several reborns (npc spawn rebornmasterdual). They will start slashig the Mutant rancor, at no avail of course. When you see that the Mutant Rancor start squashing the poor reborns, spawn a sand_creature (npc spawn sand_creature). The Sand creature will swallow a couple of reborns but then (and this is the fun part) it will swallow the mutant rancor too!!!
It doesn't matter how many MRancor I spawn they are killed by the sand creature. Only once I spawn 4 normal rancors when the sand creature came up to swallow one of them it was grabed and eated by the other rancor. Not the mutant one but the normal one!!!
I tryed to repuduce that again but it is almost impossible no matter what I trow to the sand creature it always win!!!. I also spawn a sand_creature on the table that the mutant rancor appears it grabed but then the game crashes when the sand creature starts pulling the mutant rancor.