Assassins were not very high in my "list of people I'm afraid of" as a thief even though they can see hidden because they can't lead with a permalag move and find it difficult to permalag in general. When I was the aggressor, if they tranced before I could land the KO then I bailed immediately on the fight. If they landed a big kot or big kans then I bailed immediately. Rager assassins w/ resist up, and especially those with deathblow, were beyond me regardless of trance. But the rest, and *especially those with a vuln* I probably had better-than-even odds of beating them if I landed the KO before they tranced. Land a giant backstab (buff with edge), be hasted, wield mace, exploit vulns when you can.