The phrase "play off against" implies competition and conflict between two parties. For this reason, antonyms for "play off against" might include peaceful collaboration, cooperation, and harmonious teamwork. Words that come to mind include collaborate, coordinate, cooperate, and work together. In contrast to "play off against," these words suggest a mutual goal and a desire to achieve it together. Alternatively, antonyms might include words such as isolate, separate, segregate, and divide. These words emphasize the opposite of collaboration and suggest more individualistic or confrontational behaviors. Whether working together or apart, choosing the right way to interact with others is the key to success in any situation.