As of 3.1, this potion acts completely different. From what I have tested, it will always restore the health and mana listed in the tooltip, then will give a random potion effect which can be +crit or +haste for 15 seconds, +armor for 2 minutes, the equivalent of a Runic Healing Potion or a Runic Mana Potion (only if you have mana), and probably other effects. I've also had some give no extra effects at all, but that could be because I don't have a mana pool and it tried to proc the Runic Mana Potion.
I haven't tested extensively since the randomness of the extra effect leaves this potion useless for melee. I basically used them as cheap Haste Potions pre-3.1, which cost less and also healed you, but now they seem to really only be worthwhile for mana users, if at all.