I suggest this change to her shield - it reduces spell effects according to how much % HP is left on the shield. It may be alittle complicated to implement, but it would make things interesting.

For example, at maximum shield strength, all spell effects are negated.

After losing 50% of the shield to spells, the next spell which has a magic effect only has half its potency on Morgana.

I don't know how this would work out, but.. it would seem kind of interesting. At least, i think the initial "cleansing" portion of the spell should be kept for sure. But the 8 seconds of immunity seems OP with regards to the low CD of the spell.

the shield is op due to the fact it makes her unkillable, and i do mean unkillable, iv seen whole teams gank her and she just walks away like nothing happend, hell its gotten to the point where unless your team is 10x better then the other, you all most need a morgana to even the playing field.

And 500+ magic damage can be anoying to come by, sense you have to spend much more mana to do that damage plus put your abilitys on cooldown when her shield only costs 50 mana and will be off cooldown again in a few seconds.

I fail to see how it is currently balanced, its not like morgana's other skills suck eather in fact there all vary good. As for the argument about her ult, well if this is to be taken in to account well maybe fiddlesticks needs a super shield too so he can use his ult.

If it is going to be nerfed I'd rather have the debuff clearing than the damage soak (which basically lasts one spell anyway). With CC as powerful and ubiquitous as it is more heroes need a cleanse if anything. If you take the cleanse off Morgana just becomes an iffy version of Janna, except she can't protect at all against the masssive auto-attack damage everyone can stack. If Black Shield only protects against magic damage then it's utterly useless, since the more dangerous portion of spells is always the disable, slow or root.