The Foundation Establishment Pill is a blue coloured pill that helps one to break through the shackles of the Qi Condensation realm's mortal body by purifying it and cleansing the marrow.
It is a rare pill in certain areas of the mortal world and there is more than one refinement method for these pills. A lot of the spiritual herbs required for these pills are extremely rare in the mortal realm as they are all required to be at least a thousand years old and have been plundered by cultivators of the past.