I got the Rakanishu's Blade and immediately after saw Bashiok(apparently I am pretty lucky based on my searches). I knew I had to hit Bashiok so I equipped it on my WD but I didn't know which skill I needed to use to "hit" him. I used poison dart and I didn't get the achievement.
Do I just try to run out of mana so I will have to attack him melee style? Is there a better way of disabling the skills?