What stage of glasl's model of conflict escalation marks the beginning of open and direct aggression intended to cause the opponent's public defamation?

The answer is "loss of face".

Explanation:

Loss of face is the fifth stage of Glasl's model of conflict escalation. The word face refers to the status of an individual he is having in the society. If a person is good citizen, he/she will get respect and love from other people in the society. But when we talk about loss of face, it happened when people in the society sees that person through opponents eyes and found that a person is bad and immoral.