Complex sentence: Before the final attack on The Choten's base, Tatsurion-captured by the Choten's summoning machine-is injected with the Choten's evolutionary serum, which evolves him into Evo Fury Tatsurion.
Split into simpler sentences: Before the final attack on The Choten's base, Tatsurion is captured by the Choten's summoning machine. He is later injected with the Choten's evolutionary serum, which evolves him into Evo Fury Tatsurion.