with 3.2 its different: while we are not affected with ardent defender debuff, any strike that takes us below 35% (or we take while beeing below) is reduced. with that in mind we have one goal while tanking serious stuff: do not let the build in guardian-spirit procc (we loose the damage reduction for 2 minutes after that)
so the perfect scenario is:
*hit* takes us below 35% (gets reduced)
we are getting *heal*ed back to a point where we survive the next:
*hit* takes us below 35% (gets reduced)
we are getting *heal*ed back to a point where we survive the next:
*hit* takes us below 35% (gets reduced)
... and so on
so with 3.2AD we need enough heal after hits that take us below 35% to withstand the very next one without ADs 2minutes cooldown kicking in
with thats beeing said its not our goal to use ADs-guardianspirit as a cooldown, its our goal to have an 0% uptime for the damage reduction cooldown
blooddraining helps here, no downsides. small regular heals esp. like hots are our friends now