I had plenty of fun with this bug, it works better with a mage as you can mass pull and AOE spam. I used this to farm my factions on (not naming my server) and to make some money/get items. It still works on (not naming my server) but you have to do it a different way.
The Bug Explained:
So, I figure I would explain the bug so people can understand how/why it works. The Immune bug happens because you cast ICEBLOCK or BUBBLE at the moment of death. You do not have to spam your button, you do not do it after you die, it simply just has to be about timing. Yes yes I know this has been talked about before, but I have perfected the method for doing it.
The Trick:
It can in reality work for anything that causes damage to you, but trying to judge how much damage and when they are going to attack you can be a painful process. So I found a method that is fool proof.
1. Find water deep enough that you can drown in.
2. Swim down and start the drowning process.
3. Timing - I made a macro, but you dont have to, its pretty easy. When you started to drown you lose 10% of your HP every tick. It will take 11 ticks for you to die.
4. Hold down your ICE BLOCK or BUBBLE, but do not release it yet.
5. Right before the 11th tick, release your button/key.
6. It might take you a few tries to perfect it, but if you are an icemage you can do this twice every 5 mins.
7. You know if you got the immune bug as a mage if when you die/release you still have iceblock on you. Meaning you will be a ghost with iceblock on you.
I tested this on a couple servers, and you can freely zone anywhere and keep your immunity. You can even die and keep your immunity. The immunity only goes away if you relog/DC.
Also to be noted you can do this in pvp. It is a bit harder to get, but works just the same. I usually go pvp in AB or WSG and try to time it right before someone's last cast/attack will kill me and get it. This way I can pvp and try to get the immune bug. I don't stay in the pvp area if i get the immune bug.
Be smart about this if you dont want to get banned. Go into instances and farm, stay out of popular areas and avoid PvP.