The Palm of Thousand Venoms was originally a combat technique that had been born from the Body of Thousand Immunities. But after centuries of refinement, Lord Er had managed to improve it further, making it a skill that was independent of the cultivation technique.
But even so, the Palm of Thousand Venoms was almost just as difficult to pick up as the Body of Thousand Immunities itself.
To even begin practising the combat technique, a martial artist had to first collect a long list of poisonous materials. After which, the martial artist had to expose his body to the poisons, enduring through the agony while allowing his body to absorb the essence of these poisons.
The toxicity of the poisons would then be imprinted upon the body, forming the basis of the combat technique and eventually allowing the martial artist to perform the Palm of Thousand Venoms.
So for starters, Lu Tianzi would have to gather the required poisonous materials.