Malva's Chandelure doesn't proc Flame Body? (X & Y)?

Question

My level 81 Aegislash finished off Malva's Chandelure with Shadow Claw, and for some reason Chandelure's Flame Body didn't proc. Every other time I've finished it off, I finished off with a Greninja Night Slash, and it always proc'd. I know for a fact both of these moves are physical moves. Why did this happen?

Comments

btw, what does proc mean? :P

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Proc basically means it happening. Say you are playing an RTS, and you have a burning effect on you. Each tick of damage is called a proc.

Answer 1

Flame Body won't burn every time, it only has a 30% chance to burn.

Source