It has killed my characters a couple of times too. It is particularly dangerous to elves and mages that have low hp/less defenses. I have recalled away from that beast several times, just to be on the safe side.

Some thoughts of what makes the rabid beast such an effective killer:
-The rabid beast has a good hit roll and often hits its target. Remember that AC is the primary defense mechanism for the Academy level characters. If you go there before gathering the fine leather set...

-The rabid beast is placed in the middle of the path rather than end of the cave. The newbie gets disoriented as they flee to random direction and runs back to the rabid beast accidentally while having low hp and it finishes the job.

Tarus is likely due to greed of players who try to get charred bracers too early in the game.