I tried it out too, 8:26 Hastega II with 626 skill which supports what we know, 180s base, and 1 skill = 1 second for each skill over 300. 180 + 326 = 506 seconds which is 8 mins and 26 seconds. If Beckoner set bonus kicks in, it is multiplied, sometimes up to double, I've seen 16 min Hastega II. This is tested without the set bonus, using in game timers for the minutes and using a stopwatch for the seconds and when the timer changes from 8mins to 7mins left.