Complex sentence: Milo is spared, since he redirects the Human Flame to S.T.A.R. Labs for experimental treatments, but Immortus asks him to rethink their new strategy for the future.
Split into simpler sentences: Milo is spared since he redirects the Human Flame to S.T.A.R. Labs for experimental treatments. General Immortus asks him to rethink their new strategy for the future.