Hokay, its my first post on these forums and tho i need help woud like to contribute my expirience about the topic.

After latest patch (2.1) priest Shadowfiend is counting as a normal pet and thus so it gains pet bar upon a summon but its still heavy buged like pet bar not showing up (on a clean blizz only ui tested, 0 addons), slow command response and/or no command response. Being not a macro expert i did some research and some in game testing (wich is really very boring cuz shadowfiend cooldown is 5 min) and the best macro i coud come up with was

/cast Shadowfiend(Rank 1)
/petattack <target>
/petaggressive

tho sometimes this works some time, due some to me unknown error, it doesnt, my intent was to make a macro that would cast shadowfiend and obviously focus his attacks immediately on my current target and keep attacking that target no matter what. This macro is most important to me @ raid environment cuz wasting a shadowfiend on a lets say Void reaver really hurts. Now my questions, have anyone tested this and made a usable macro or does anyone have a suggestion how to solve this. Atm i either use the macro or just spam pet attack key binding after i cast fiend but that also doesnt seem as the best solution cuz some times he goes for the target then all of a sudden stops and start coming back and then i start spaming so he basicly spend its short duration going there and back wich makes me wanna smash some gnome head right there.

Is shadowfiend ultimately buged and its behavior cant really be predicted/directed 100%?

Any help, about making macro or resolving this woud tremendously help.

You should add a /stopcasting after you cast shadowfiend and I would also add a /stocasting after the other commands. So it should be:

/stopcasting is worthless after a GCD spell. /petattack won't work like you want it. Pet won't be active when /petattack will be issued. So you have to press the button twice.
or (because switching pet stances resets their aggro/target, so telling pet to attack then moving it to aggressive will just make it go to nearest target afaik )

(not sure about stopcasting and petattack petaggresive)

I use

but really any of these will work, you just have to hit the button more than once.

There's a keybind for "Pet Attack" in the options, works for me. The fiend likes to give up when the mob get hits with slow/stun sometimes, but spamming the bind makes it stick pretty well.