I tried it last night, and I was unable to charm the bull in the pond (Old Miller's bull). It would be nice to charm it, but I guess since it is a quest beast it would leave to paradoxial quest problems - you can't kill your own pet directly. Also for those ranger folks beast mastery seems to directly affect how agressive your beast is. At a level 0 borrowed beast mastery a charmed lv 5 stalker will attack when it gets around to it. On my M/R with about a 2/3 beast mastery (didn't play him last night) my Lv 8 stalker would attack as soon as I targeted something.
Also, bears are hard to charm by yourself even when trapped by inaccessible(sp) terrain. I tried to charm a lone bear (in regency forest) but his "break charm" was too strong for my 0 beast master ability. I might try again after I sub-professionalize my warrior in the ranger ways.
So sad about the bull - I would abandon the quest to charm him.
b

