Whirlpool is indeed a great skill to use in many situations but I disagree with a statement/assumption that if you can't kill a single poison-immune target (boss?) with your everyday gear you have to forget about everything and start making Whirlpool boots aka You shall not pass until you get Whirlpool oskill.
as if it is hard to roll that oskill - this skill also usually saves my ass in vizjun - hit it into a big pack and your life is almost full all the time while you rush further to the boss !