Flare Blitz has a BP of 120. Life Orb and Sheer Force together boost that by 50%, and 50% of 120 is 60, so 120 + 60 is 180. STAB boosts thatby 50%, or 90, so it's power then comes up to
270. Coming off of Darmanitan's mostrous attack, that is gonna be doing unfathomable damage to even Pokemon that resist it.
As an extra perk, that is doing 540 BP in the sun, which is completely insane.