On Val there is a secret fire wyvern trench. So you go into the ice wyvern trench as usual then you go into the end and there is a little hole that leads to the fire wyvern one. Be careful and bring fur for the ice part then switch to ghille in fire part. There is lava in the fire part also and watch out for ice wyvern while getting fire eggs. I’m pretty sure there is a second entrance that you can use to escape the fire trench.