jamiek
I don't know how exactly you've set up the damage and how long you want to be hit for and for the particle to be displayed etc but you can use :
Every tick > set particle position to Player.X, Player.Y.
This would set it to player position constantly (give the effect of pinning) until destroyed.
A possible destroy event might be after the particle hit effects have shown for a few seconds then you can say:
On particle created > wait 3 seconds > destroy.
It will obviously require some tweaking if you want to stop particle effects during certain scenarios. It all depends on what exactly what you want but it will all be possible in C2