Once they have passed all ICE on a Server, they access all cards installed in that Server, and, depending on which Server they attacked, either a random card from the Corp's hand, the top card of the Corp's deck or all cards in the discard pile
Finally, its a form of massive card advantage since you can discard the lands for effects like Cathartic Reunion or Seismic Assault
While official starter products are a fine way to get into the game, bulk card lots like these can clear closet space for the experienced player and cheaply give the novice a huge set of toys to play with
Be that as it may, it is rather interesting to observe how the game design and power level has grown incrementally over the past decade
Any Limited player who has taken a hard mulligan can tell you how much one card matters
Its the kind of annoyance that builds up into something horrible