Complex sentence: During the events of "Type-0", Machina became a Byakko l'Cie and was forced to kill Rem before joining her in crystal stasis and later revived by Arecia to rebuild Orience once the crystals are removed.
Split into simpler sentences: During the events of "Type-0", Machina became a Byakko l'Cie and was forced to kill Rem before joining her in crystal stasis. He is later revived by Arecia to rebuild Orience once the crystals are removed.