Taiz

Tshell is a better choice than serenity hands down now, the immune to interrupt and stun doesn't work on any encounter ya need it. However I only find my self using Tshell on a hand full of encounters also there are a ton of aoe's that go right through it aswell as using tshell and a ae being late is the worst thing ever wish we could get rid of that damn stifle..

Syrah

I don't remember the last time I was spec'd for Serenity. I think it was during the KoS expansion. I have always gone down the AGI & INT line because Serenity is useless for most fights.