For Magic Defense There IS Coral Rings I know higher level but they are also -% Magical Damage taken rather than MDB too! Also to add they are alot cheaper. (well on my server at the moment any ways)
Useful for exp'ing on imps, they cast quite frequently and the defense is an added bonus to your magic defense setup. Having a mdb set will help your healer out alot more then just your self cast shell.