"Paladin, do you have the courage to sacrifice yourself for the greater good?"
This was a question asked by most Paladin NPCs, and represented the Paladins' virtues.
Sacrificing themselves and saving others was the greatest expression of those virtues.
Officially, the Paladin's Divine Intervention gave a target an effect which prevented Bosses from attacking them. After the Boss left, the target player could then cancel the effect and revive the other players.
If you heard your teammates asking you to use Divine Intervention, it was best to stay as far away from the monster as possible.
If you were the target of Divine Intervention, you wouldn't want the duration to end while you were in vulnerable position. If you were the teammate of a Divine Intervention target, you had to die quickly. Otherwise, if the Divine Intervention ended and you were still alive… it would truly be a waste.