Spider2458

I am making my first mod, and I need help with one aspect of it. I need to the sword to have a certain potion effect on mobs when it attacks one. I have searched the internet and haven't found anything related to this. For Example, It gives a mob the slowness effect for, 10 seconds. If it helps the matter, the Unlocalized name of the Sword is "itemIcySword". If anyone has any idea how I can implement this, than please do tell me. I would really appreciate it.