The phrase "hammers out deal" typically refers to a process where two or more parties negotiate and come to an agreement on a matter. The antonyms of this phrase would be those that describe the opposite of this process. Some possible antonyms for "hammers out deal" could include "stalls negotiations," "breaks off talks," "refuses to compromise," "fails to reach an agreement," or "disputes terms." These antonyms suggest a lack of progress, inability to find common ground, or even hostility between parties. While "hammers out deal" implies a successful outcome, its antonyms describe a frustrating or unsuccessful negotiation process.