The Thorns enchanment, at least Thorns II seems to be having the opposite effect.
I enchanted a iron chest through an enchanting table with 30 levels and got Thorns II Unbreaking III and Blast Protection II. Upon hitting mobs I would occasionally take the thorn damage myself, Instead of them hitting me and taking the damage.
Steps to Reproduce:
1. Enchant iron chest wiith Thorns II
2. Hit mobs
3. Take damage.
3. ...
Linked issues
duplicates 1
Comments 2
Duplicate of MC-29866, please use the search function to see if your bug has already been submitted. Currently over 57% of tickets are being resolved as duplicate.
Were the mobs wearing enchanted armor of their own? Are you sure they weren't hitting you at the same time? Or could another mob have been hitting you from behind?