Appropriate times to use Clemency?

[Karshan]

Never. Healers adjust.

Kidding, it's just that we don't know yet what the MP regen rates (passive and from skills) will be, if it's like StB you need every MP for your Requi phases, even more so that now refresh / manashift is gone.

Of course, if it's like O6S, and you're feeling like your healer is forgetting you a bit cause he is playing picasso, you pop one out, staying alive trumps a Holy spirit anytime.

If you're OTanking, it's better to avoid at all the dangerous low health situation for the MT, by a correct usage of Cover and Intervention, or even emergency vokes to take that TB from hell, rather than Clemency. Unless of course your healer is in a pinch and/or asks you to out of desperation.