Why does Clemency get interrupted? And why does Sword/Shield Oath reset combo?

[Giantbane]

Given that we have PLD at one end (2 GCDs, highest mana cost), Warrior at the other (no GCD loss, possible health loss and slower eHP increase), and DRK exactly in the middle of that 'ease of swapping' spectrum (1 GCD loss, moderate mana cost)...

In reality, the PLD only loses time. MP is meaningless to PLD in the vast majority of situations where they'd even consider stance dancing. The MP a DRK spends always means lost damage, since excess MP can always be used to dump into DA + SE (or DA + DP if you've really got an excess of MP). So in practice, the PLD is losing 2x GCD worth of damage, while the DRK is losing 1 GCD and another ~85ish potency (75% of the difference between a DE and a DA + SE). I mean, DRK still has it better than the poor PLD at this point, but it's worth understanding.

The health that the WAR loses should be considered significant. But they also have, hands down, the best self healing among the 3 tanks, so it's sort of moo.