There are three cards, however, that cause creatures to lose all their creature types, adding another dimension to tribal gameplay while still underscoring the importance of creature types.
Nameless Inversion, as a cheap Last Gasp-style removal spell that is tutorable with the tribal Harbingers, was all over Worlds 2007. Its art showcases both aspects—the victim is shown stretched out to odd proportions, with spindly legs and huge arms and hands. And, to represent the "loses all creature types" effect, the being has no face.
Similarly, Ego Erasure erases all creature types from your opponent's entire team, which can have a devastating effect against any +1/+1 "lords" (such as Wizened Cenn or Imperious Perfect) that your opponent might have, in addition to the -2/-0 havoc the spell already wreaks. The faceless motif was continued in its art as well—here we see two elves as the victim of Ego Erasure.
Amoeboid Changeling doesn't repeat the "faceless" visual cue; it's usually not the victim of its own ability. Instead, as it's one of the most flexible changelings of all, granting all creature types or taking them away as needed, it's shown with a very flexible shape: that of an amorphous blob.