In Phase 10, can you draw any card from the discard pile or just the top card?
You can only draw the top of the discard pile. From the rules:


  On your turn, draw one card, either the top card from the draw pile or the top card from the discard pile, and add it to your hand. End your turn by discarding any one of your cards onto the top of the discard pile.


So the discard pile is 1 single stack, like the draw pile, with only the top card visible.