my BiB suggest me to use Void-Twisted Titanshard but it just feels bad.
Running a simmulation with the length of around 270s says that void shroud has a uptime of ~23.7%. That would translate into ~64s, with the proc-count beeing around ~5 times, Void shroud would be up for approximitly 12.8s of the 15sec duration which i feel like is pretty unrealistic as a shield of ~70k hp is drained pretty quickly with corruption and raid mechanics.
Warcraftlog rankings also suggest that coral+Vita-Charged titanshard is still the better choice instead of the complete titan shard set for enhancement shamen.
My Addon Export: