Complex sentence: Thanks to Skye helping to regain control of Mike Peterson, Garrett was badly defeated by Peterson but evades arrest and upgrades himself, however, is then killed by Coulson using the 0-8-4 weapon.
Split into simpler sentences: Thanks to Skye helping to regain control of Mike Peterson, Garrett was badly defeated by Peterson. After evading arrest and upgrading himself, Garrett is then killed by Coulson using the 0-8-4 weapon.