This is actually the last post for series 5 as we haven't had much on the new aliens front at all and the final episodes only feature returning classic foes in a well-paced and scripted finale. While it was nice to see Daleks, Cybermen, Judoon and a host of other used in a meaningful 'bigger than ever' way it doesn't give us much to go on till Christmas.
Krafaysis, now that's an alien name! Weird unusual and with a familiar hint of Sci-Fi to it unlike the Waspyforms and Fire-o-viles we're normally stuck with. This was classic monster, big, strange and dangerous and to make it more fun invisible on top. The dynamic of only one team member seeing it added to the suspense and while some of the invisible fights left a little to be desired on the whole it was carried off, and the plot line of it being invisible and therefore blind worked well to make it just a creature not another race prepped for world takeover.
Krafaysis is a large species of predators capable of traveling between the stars. As an aid to hunt they were invisible to the naked eye, this also rendered them blind, though they could rely on their excellent hearing and other sense to hunt in co-ordinated packs. Occasionally one would be left behind, as happened when Vincent Van Gogh, who was able to perceive them due to his incredible eye for nature, met one, lone rampaging as it desperately tried to survive killing all who were unfortunate enough to get in it's way.
That's all folks - more Who at Christmas