In the act of infiltrating a castle or a fortress, the key to success would always be silence and swiftness. Wang Ling was all too aware of this and moved like so.
Not letting anything pass his attention, he and Bai Xue moved like shadows that have no corporeal body. They killed by breaking the neck of the guards and the hidden forces.
They didn't resort to any bloodshed, blood splash might reveal their positions. If they ever needed to kill with a sword or something that will spill blood. Bai Xue would suck up all the blood from the ground and drink it like juice.
However, as they entered inside. They made sure to first interrogate someone and ask them where their master stayed. They asked three people and only did what they told them after confirming the truth. Wang Ling and Bai Xue killed those who gave them information. It was a painless death.