Use a Finding Charm to increase the chances we'd find a Nergigante egg with decent genes.Here are the steps we took to get a Nergigante egg: You must instead search Rare Monster Dens and hope the egg appears. It's impossible to force a Nergigante back to its den, and it will never retreat after a fight. Once defeated, there is, unfortunately, no way to guarantee a Nergigante egg spawns. Nergigante is weak to Thunder, so using Zinogre or Astalos weapons as well as Zinogre and Astalos themselves will be advantageous. First, you must defeat Nergigante in Terga as part of the story.