Trainer/Supporter can benefit you (and your opponent) in multiple ways
Its one thing for a combo to win a game and end it, but the worst banned cards will stop your opponents from doing anything from early in the game (think about cheating out a Sundering Titan on turn 1), but wont let you win for a long time
While slightly higher on the mana cost scale than most other Elves, Dionus comes with a strong ability to make it worth it
You'll eventually want to supplement what you have with better cards that you want, and this is your best bet at getting what you're looking for
And with Cosmic Spider-Man to give everyone haste and lifelink, these attacks not only end games quickly but also maintain your life total, which keeps you safe while your opponents crumble
That ratio has remained the same since Outlaws of Thunder Junction , but starting with Edge of Eternities , art cards will be exclusive to Collector boosters