Power: I have heard the "which superpower is best" discussion before, and shapeshifting always seems to come out on top because it has all the others as a bonus as long as you know someone who has those powers; therefore, it was my knee-jerk response. However, I'm going to have to go with the magic/telepathy combination as implemented in the Inheritance Cycle (Eragon) because, since it's emphasized over and over again in the books that the ability is all mental, I think it might not be attainable through shapeshifting. For the uninitiated, this magic has literally no limits on versatility (you cast spells by willing your magic to activate and then describing in Elvish what you want to do; the wording doesn't matter). Infinite versatility? I could still shapeshift; it would just take a minute or two to transform. There are two rules for this magic. 1: the energy used is taken from your own body (so lifting a stone with magic tires you by exactly the same amount as lifting it by hand...actually slightly less, since with magic you don't have to also lift your arm; this also means you need to keep E=mc^2 in mind). 2: the energy required to do something increases with distance.