<spoiler>Part of the Killing in the Name of... Quest.
Teleport leading to the boss is upstairs in east tunnel of deapest floor of cyclopolis.</spoiler>
Location:
Stonecracker spawns near the stairs leading to the Behemoth Quest room, in the deepest floor of Cyclopolis. Its possible that Stonecracker spawns after the lvl 30 door (as shown in the image), there he spawn with 3 other Behemoths.