as it stands it is not Reflecting anything, its a trap. it seems ur objection is that it blocks a spell, how about if i change it to taking 5/10/15/20/25% damage off the top of the spell. honestly though its mostly a damage spell, however it has only a short window to work, you practically have to cast as the skill shot or cast goes off. i felt that that coupled with its cd and mana cost gave it a right to hit like a mage nuke
this character was not made to be easy, and it takes real skill to get the traps sprung without getting killed. on top of that you are seeing an extreme mage build version of him to give you an idea of the caps, its safer and easier to play him tank but u wont get nearly as much damage that way. so if u play him the way i am showing, you would have to be a squishy mage anyway. if you look at tanks on the other hand, nunu has a 1.0 on snow ball and a 2.0 on ult, both hurt a lot but he is manageable. another concept that some may not have noticed is that he could be built ad. his clone does all the damage he does but can be killed with a single skill.