Complex sentence: Amidst the growing tensions, tragedy strikes Akira causing his mind to snap, retreating into his subconscious, allowing his Devilish alter-ego Amon to break free from Akira's cage of flesh and wreak havoc on both human and demons alike.
Split into simpler sentences: Amidst the growing tensions, tragedy strikes Akira causing his mind to snap. Retreating into his subconscious, this allows his devilish alter-ego Amon to break free from Akira's cage of flesh and wreak havoc on both human and demons alike.