Well, its all about coordination and talking. You can ask the WHM to wait for stun locking or you can wait the stun lock come to an end to use your Blood Price. Second option is a bit easier to do with PUGs if you're the DRK. Worry not, if the WHM starts stun locking, the monsters will get full stun resist before they die. So you have plenty of time to recover your mana. Holy's power in dungeons comes not only on its Spammable High Potency but also in its powerfull mitigation wich alongside with tank defensive abilities and a strong regen can make the tank be safe for a long time while the healer is dealing massive damage.
