Using Potions While Shapeshifted

As discussed like wildfire in the WoW forums, using a macro, Druids can now drink potions while shapeshifted. This is because of the cancelform feature added in the 2.3 patch. Here is an example macro:
#show Super Healing Potion
/cancelform
/use Super Healing Potion
/use Master Healthstone
/cast Dire Bear Form
Limitations and misconceptions:
- It only works with items that do not trigger a global cooldown.
- You must not currently be under a global cooldown.
- Don’t hit the macro quickly twice in a row.
- You must have enough mana to shift back.
- You WILL NOT get hit out of form.
What does this mean and why does it work? It works because cancelform doesn’t trigger a global cooldown. To understand this let’s look at what the global cooldown is. Most abilities and items in the game trigger a timer that lasts 1-1.5 seconds. During that timer, you must wait before you can do something else. This is partly so you can’t button mash some buttons over and over to high speed victory. But more importantly in this case it’s so the server and the client, blizzard’s server and your computer, need time to exchange information on what’s happening during the fight.
Drinking potions and using healthstones don’t trigger a global cooldown. That means this macro has one line that does, the last one which shifts back to form. So as far as the server is concerned everything in the macro happens all at once. The only time this isn’t true, and the only time you are at risk of getting hit during that instantaneous time that you are out of form, is when your computer takes more time to apply the change than the latency to blizzard’s server. This is effectively never.
There are two risks. You must make sure you have enough mana in caster form to switch back. This is rarely a problem as a bear or cat, unless you are doing a lot of shifting. And the other is that you must be sure you aren’t currently under a cooldown. If you are then the last line in the macro will fail and you will be left in caster form. So wait 1.5 seconds since your last mangle, shread, or other ability before using the macro. And don’t button mash and hit the macro more than one time.
How useful is this? It’s useful as an emergency ability as a tank. And it’s handy for cat form when healers don’t have time to throw heals on you during a fight.
I’d read about this long ago. Tried it a few times. Wiped a few groups/raids doing so (including one really close fight vs. Akil’azon)
I always seem to end up in caster form after the macro casts. I hadn’t considered that I might be in GCD when I tried it though. Maybe I’ll give raid-wiping one more shot.
It’s most helpful in cat form. Bear form has so many hitpoints that one extra potion of health isn’t too much. Useful in an emergency either way.