Find the Blessed Horn in The Wengari Fortress.
To reach the Lance of Heorot, you must access a portal inside The Temple of Heorot. To do that, you will need the Blessed Horn, a relic guarded by a nomadic tribe last seen to the west of Heoborea.
After traveling west, you found the camp of the nomads under attack by the Wengari. You dispatched the Wengari and saved the survivors. Upon speaking with them, you learn that the Blessed Horn was stolen by the Wengari and likely taken back to their domain.
You must storm The Wengari Fortress to retrieve the Blessed Horn!