Bringing back some old school.
Slugslider - A giant slug that can slide and self propel along ice and snow. Slugsliders grow thick armor that their malleable bodies can manipulate and use as weapons.
This was from 2010 when the first public talk was received about end game ideas and visions along with some concept art. Monster abilities have always been present but dormant (well over 400 still dormant), some descriptions fit what we know in the current version some yet to be seen. This was a sneak peak with concept art and it's in game rendition.