Complex sentence: However Ronan the Accuser does not honor the peace treaty and obtains an Infinity Stone and attempts to use it to destroy the planet, only to be thwarted by the Guardians of the Galaxy.
Split into simpler sentences: However Ronan the Accuser does not honor the peace treaty. Ronan obtains an Infinity Stone and attempts to use it to destroy the planet, only to be thwarted by the Guardians of the Galaxy.