Complex sentence: While Simon distracts the goblins, Mallory and Jared manage to reach a tunnel under the estate, though they are pursued by a mole troll and only narrowly escape it when it is struck by an oncoming vehicle.
Split into simpler sentences: While Simon distracts the goblins, Mallory and Jared manage to reach a tunnel under the estate. However, they are pursued by a mole troll and only narrowly escape it when it is struck by an oncoming vehicle.