This is a puja that we practice once every month. The Garchen Institute explain this practice as:

Guru Yoga meditation practice is one of the most important and effective methods for attaining enlightenment. Lama Chopa is the Guru Yoga Practice of Lord Jigten Sumgon, the incarnation of Arya Nagarjuna and the founder of the Drikung Kagyu Lineage. Lord Jigten Sumgon says, “From today on, with one-pointed devotion pray to your great master and practice according to what he teaches. Thus, it is certain you will achieve the ultimate accomplishment (Buddhahood).” This practice is a complete meditation for purifying the four obscurations through receiving the four empowerments and transforming one’s body, speech, and mind into the pure enlightened state.

The puja
Below is an excerpt from a Lama Chopa and Tsok lead by H.E. Garchen Rinpoche

Lama Chopa Teachings with Garchen Rinpoche, March 2014