Amumu passive update?

Reduces MR with autos. So many better options. 2 second slow with auto on one target every 15 secs. Cursed burn when damaging enemies with spells. Reduced MR aura. Just clunky and seems out of place with the kit and champ in general. What about increased damage by 5% when he "hugs" them. When attacked slows the enemy for 1 second, only every 15 secs or so. Idk I just would like to see a more useful passive. It just seems so plain