Firstly, Lu Li used some elixirs to reach a certain level of DPS. To make sure that they had enough DPS, Lu Li didn't bring many healers with him. One small squad was sufficient.
Therefore, the party would have to use their potions and elixirs sparingly. If they needed to, they should just drink them, because if they died, they would be revived back at the checkpoint. This meant that they would also have to run back to the battle, which was a long way.
Lu Li also hesitantly purchased an additional mobile checkpoint. It was definitely useful, as when the players died, they would revive at this checkpoint, instead of the original one. The checkpoint looked like an angel statue, and the price was 200 gold.