How to make it so that when a mob hit you get a potion effect

[Brandonbr1_nug]

Hi I would like to how how  it is so that when a mob hits you it gives you the potion (poison) effect for 4 seconds

[uSkizzik]

First off, override the hurt method.
You'll get the DamageSource from which you can get the entity.
After that do a null check on it and check if it's an instance of LivingEntity (or Mob).
If it is, you can apply the effect.