@Jimsock1 I'm guessing it's phantom pain, It's a skill that deals no damage hence no pain... I think it's just a common reaction like imagine you got the skill you'd still flinch, block, and/or dodge attacks despite being immune to everything
To sum it up,
Brain: You got hit so.. uh guess I'll send pain your way!
You: But I got a skill with no damage
Brain: Pain!