Fight some of them again
A group wipes out when all party members die and have no way to resurrect themselves. They have to run back to the dungeon from the graveyard and start from the beginning of the dungeon again. Depending on the dungeon and the length of time since you first entered, monsters may have rescanned and you might have to fight some of them again. If you are lucky, the monsters you killed previously will all still be dead, and you can run right back to where you last were. Do not think you are waste time and power. Requiem gold is really good for you if you play this game.