Complex sentence: When the War in Hell broke out over the souls of The Chosen, Karnak killed Tox'xel, Sirilleth, and afterwards, hurled his spear into the midst of The Chosen, causing a chain reaction that killed Baaleth, Helixia, and hundreds of other souls.
Split into simpler sentences: When the War in Hell broke out over the souls of The Chosen, Karnak decided to kill Tox'xel. He killed Tox'xel, Sirilleth, and afterwards, hurled his spear into the midst of The Chosen, causing a chain reaction that killed Baaleth, Helixia, and hundreds of other souls.