It all depends on the alliance you have and how many Executioners the Feeler pops. If you have a good group you can quickly get him to pop a mob, and if its not Alastor, kill it rather fast, and then repeat. Smaller group, kill times for each executioner go up. Theres really just no way of knowing, but I'd assume at least 30min per fight minimum (including the ??? repop). Odds are it'll be more, but theres that huge luck factor in how fast Alastor shows up. I've seen him show first spawn, and one time I think he was the 13th or something ridiculous.
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