Yes, I finally managed to make Tazik do what he's supposed to. Basically, he does it when certain conditions are met on the battlefield, but for some reason, I thought he would do it right away, and seeing that nothing happened after 2-3 rounds, I didn't even bother to test this theory further.
Tazik requires a certain "lure" from the player; I would even say a substantial lure. But after that, it's just a matter of technique. =)
Actually, I wrote about this a few days ago in a comment on the map on heroesportal.net, where I downloaded it, but it seems like that site is "dead" and my comment will never appear there.
There also seems to be some problem with new maps for HotA. They simply don't open, including mine. Maybe not all of them, but many.