Altar of Kron
The Altar of Kron is the highest place in Magnarok, reached by following the Ascent of Frostfire. Here, the magnaron Kron keeps the fury Exurotus contained to use its energies for the great work. Drek'Thar and Thrall confronted the magnaron and slew him to free Exurotus.
Otherwise, the magnaron Vrok the Ancient can be found battling a fury of fire at the altar.