Noticing that the previous contributor to these achievement solutions stopped posting, I will pick up the torch were a great man once stood by using his format for the rest of the guide
*** Spoiler - click to reveal ***Now teamed up with Catwoman, take out 3 guards with QTEs.
You will confront The Pact with QTEs, when all hope is lost. SURPRISE John helps you out. More QTEs in the most baddass fight sequence in the game.
Harley escapes leaving all of The Pact behind, while the agency shows up
After title card you will have a conversation with Waller, then be convinced to have a conversation with Mr. Freeze
You will choose to either lower temperature or walk away
You leave the lab
End of Chapter