Aside from the fact that this is probably the most cataclysmic event the game has ever seen story-wise, it's also the first set in an extremely long time to introduce a new card type, as well as just generally being jam packed full of crazy legends, double sided cards, new mechanics, and more
This card was released in 1999, and it began the Tropical Series tradition
Since it builds up experience counters by seeing other colorless creatures die, you should build up a board first, then cast Azlask once you have a few on-demand ways to build up experience
Theyve all crept up in price (ok, not so much the green one), and generally have evaded reprints to this point
Even without its effect, a 3/2 with trample is a solid body
If Wizards of the Coast decided to incinerate everyones Magic Online collections tomorrow, why would they stick around and wait for yet another Wizards of the Coast product instead of bailing for Hearthstone or Eternal