The underside of the horn boasts an emblazoned seal with a hammer and lightning bolt. Something about the horn seems extremely out of place on a Magnataur.
Take the horn south down the Path of the Titans to Wyrmrest and seek out someone who might be interested in these threatening implications.
Rewards
You will also receive: 5 30
Progress
Yes, <race>?
Completion
It is indeed strange for any magnataur to carry an item such as this... and very concerning. I am glad that you have shown this to me.