While the casting cost is somewhat prohibitive, but if you have, say, nine Slivers in play, or, I dont know, 17 Elves, theyll get +8/+8 and +16/+16, respectively not bad for you Timmys and Tammys out there
From a psychology perspective, it also gooses interest to have something sell out early, and push hype towards getting the rest of it sold
Indigo-Eyes Silver Dragon
Why not rolling dice for cards as well
Instead, you can engage in rudimentary battles against AI and other players, open packs by waiting for the timer or rushing it via Hourglass objects that you get your hands on by completing missions, and these tend to complete themselves just by you playing
One notable new card that was dropped into every deck was Myriad Landscape, a neat little card that let you go dig up two basics to put onto the battlefield