Complex sentence: English warns Pegasus of the threat, but unknowingly imbibes the drink containing the drug, rendering him vulnerable to Ambrose's commands, the first of which is to subdue Pegasus after she berates Ambrose as a traitor which he does with a punch to the face.
Split into simpler sentences: English warns Pegasus of the threat, but unknowingly imbibes the drink containing the drug. Ambrose tells English to subdue Pegasus, which he does with a punch to the face.