Decided to try beat old speedrun record (1,47s by Marco, assassin).
Also beat laz without deaths and using skill slow (screaming eagle), which makes it quite bit easier to do.
Few points:
Even though I successfully hit with first purify at 20s mark of speedrun (2 first are dodged), I still managed to beat old record by 1s. Secret? Banish oskill (-22% HP that lasts entire fight, 300s duration), one cast of it at 00:15. If first purify isn't dodged by laz, result could be better by ~15s.
Here is example of other failed run, hp with banish on, and after banish expired:
http://i.imgur.com/98YuRNj.jpg
enjoy