Ista Cale camp - runic message on the pillar

[Frankly,]

So at the Bloodless Hunter camp I found a pillar with a locked mountain door next to it. The pillar had a message in Amythevian runes. I translated them (several times, pretty damn sure its correct), and i've got TENRAK. What do I do about this?

[Mortmal]

Not found it either , you are supposed to use the linguist book and type it in an incantation but i cant figure wich one.

[Eyestolks]

Look into Erlein's Handbook. The incantation is nufri <runes>. And yes, TENRAK is correct.
There are some other useful incantations in the handbook as well.