I used Snazaroo in the past and seriously, I don't like it because your face will look marbled and you need several layers of makeup to no have this effect...
So I'd suggest Ben Nye, which is mostly opaque and high pigmented, but you must set it with powder ! Ben Nye or Graftobian loose powders work well
it's long lasting and even water resistant
Here's me with Porcelain by Ben Nye skintone to show you how opaque it is :
and the Ben Nye color chart if you need
Cadaver Grey could be something interesting for a Homestuck troll http://prymeartistry.com/wp-content/...colourcake.jpg
Hope it helped !