Complex sentence: Ork Warboss Grimskull is eventually killed by Titus which breaks the Orks coordination and renders them no longer a major threat as they fight each other, the Titan named Invictus is powered up by the Experimental Device, and destroys The Spire.
Split into simpler sentences: Ork Warboss Grimskull is eventually killed by Titus which breaks the Orks' coordination and renders them no longer a major threat as they fight each other. The Titan named Invictus is powered up by the Experimental Device, and destroys The Spire.