Flaming Crush is a 3-hit hybrid WS, similar to Jinpu or Chi. So:
First hit - 6 fTP physical, 6 fTP magical (You can think of it like an en-effect that mirrors the damage of the physical hit)
Second hit - 1 fTP physical
Third hit - 1 fTP physical
The first hit's physical and magical components share the same pDIF, so if it crits then you get a massive damage increase (see above). The Magic component is affected by MAB, so you can amplify it with all the readily available Avatar MAB gear and more than double your damage.