I need something big and scary enough to scar a hord of orcs off their mountain. /u/LordTyler123 DnD: Roll for Initiative!

I’m going to throw a horde of orc at my lvl 4 party but I need some bigger threat to put behind the horde. The difrent tribes had lived on the mountain happy to kill each other for decades but something united them under a single warboss and they decended off the mountain to rip and tear up everything. After repelling the horde and killing the boss the horde will split up and the boss’s much more reasonable son will reveal the horde united to fight something but they lost and were driven off.

My savage orcs tribes are just as suicidally war hungry as original dnd so wat could be bad enough to make orcs run away from a glorious death? I was thinking a dragon with a lizard army but that duesnt feel enough Magical fear? Big monster? Erupting volcano?

I’m going to throw a horde of orc at my lvl 4 party but I need some bigger threat to put behind the horde. The difrent tribes had lived on the mountain happy to kill each other for decades but something united them under a single warboss and they decended off the mountain to rip and tear up everything. After repelling the horde and killing the boss the horde will split up and the boss’s much more reasonable son will reveal the horde united to fight something but they lost and were driven off.

My savage orcs tribes are just as suicidally war hungry as original dnd so wat could be bad enough to make orcs run away from a glorious death? I was thinking a dragon with a lizard army but that duesnt feel enough Magical fear? Big monster? Erupting volcano?