I am at the ender dragon and have tons of Potions of instant damage. I never got into range, but do the effects even do anything?
From the minecraft Wiki under "Bugs":
So, to answer the question: No. But this might change in future versions.
protected by Frank Feb 8 '15 at 14:47
Thank you for your interest in this question.
Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
Would you like to answer one of these unanswered questions instead?