I like building casual decks based around obscure rares. This one has been sitting in my collection forever, and I've never used it. I'm completely stumped.
Thran Lens is a two mana artifact that reads
All permanents are colorless.
Other than making Black creatures vulnerable to Dark Banishing and the like, what is this card good for? My ideal deck would use the Lens as part of a winning, or at least very annoying combo. I'm not worried about how feasible the combo is to execute - Rube Goldberg machines based on many cards are welcome.
There is one important extra caveat. My collection is strictly old-school. I can only use cards from Scourge or earlier, since those are the only cards I possess (or am willing to buy). On the plus side, I do have most of them...