Complex sentence: Gilgamesh's first appearance is in "Final Fantasy V" as a major villain, who the party encounters several times before he is banished to the Rift by Exdeath for his repeated failures.
Split into simpler sentences: Gilgamesh's first appearance is in "Final Fantasy V" as a major villain, who the party encounters several times. Before he was banished to the Rift by Exdeath for his repeated failures.