Fate/Apocrypha - S01

The Holy Grail is an ancient relic of immense power, said to grant any wish to those who possess it. To seize this power, magi called "masters" summon legendary warriors known as "servants" to battle in a deadly contest called the Holy Grail War. Only the last surviving master and servant can claim the Grail. However, the third war ended without a victor when the Grail vanished mysteriously after the fighting. Years later, the magi clan Yggdmillennia reveals they hold the Holy Grail and plan to break away from the Mage's Association. The Association dispatches 50 elite magi to reclaim it, but all except one are slaughtered by an unidentified servant. The survivor is sent back as a messenger, delivering Yggdmillennia's declaration of war. With only two factions involved, this Holy Grail War unfolds differently. Both Yggdmillennia and the Mage's Association will field seven master-servant pairs, and the first side to lose all their fighters must surrender the Grail. As the 14 masters summon their servants and prepare for battle, the magical world trembles at the dawn of the Great Holy Grail War.