Killing Maia

[Knight of Gondor]

I searched this doggone forum, but I couldn't find any threads, so don't shut me down if this is a repeat?

I just noticed that Sauron loses his bodily form several times in Middle-Earth (at the hand of Huan and Luthien, perishing in Akallabeth, at the Last Alliance, etc. How many times can Sauron lose his bodily form and yet regain it? Likewise with the Nazgul...they took a while to regain their form after the flood swept them away. How long does it take? What does it entail? "Come on back to the 'form' room, Witchking, let's see if we've got a form that will fit you."