The one from Wotlk :
Sacred Shield :
Each time the target takes damage they gain a Sacred Shield, absorbing 500 damage and increasing the paladin’s chance to critically hit with Flash of Light by 50% for up to 6 sec. They cannot gain this effect more than once every 6 sec. Lasts 30 sec. This spell cannot be on more than one target at any one time.
Not OP but still good in the current meta.