'Justice' was done, and the President of the Immortals (in Aeschylean phrase) had ended his sport with Tess. (59.8)
The reference to a play by the ancient Greek playwright, Aeschylus, seems at first kind of out of place here. But Aeschylus wrote tragedies, and the phrase that Hardy borrows, the "President of the Immortals," comes from Aeschylus's play, Prometheus, and Prometheus was considered by many to be the ultimate tragic hero. That play is all about punishment and justice, so it's an appropriate reference at this point in Tess. You should also note that "justice" is ironically set off in quotation marks in this passage.