Complex sentence: Thanos then leaves Earth, and prepares to use the Infinity Gauntlet to rule the universe before the Avengers face him in "Thanos Triumphant" using battle mechs built from reverse-engineering Titan technology.
Split into simpler sentences: Thanos then leaves Earth, and prepares to use the Infinity Gauntlet to rule the universe. However, the Avengers arrive in battle mechs built from reverse-engineering Titan technology.