Chieftain Hrungrod, leader of the ice-giants, helped the Angmarim lure you into a trap.
'The ice-giant leader, Chieftain Hrungrod, lured us into a trap. It will be a tough fight for just the two of us, but I am willing to make him pay for it if you are.'
Chieftain Hrungrod can be found in his throne room in Thyrstáth.
You should defeat Chieftain Hrungrod.
Use the summoning horn to call Hórin to your side.
You should talk to Hórin.
If Hórin is no longer with you, you can find him at Fellgát.