For example, if you control three creatures and two Starlight Spectaculars, each Spectacular will give one creature +0/+0, another +1/+1 and the third +2/+2
If you love the game, its important that Wizards of the Coast thrives, and promotions like this make a big difference to the companys bottom line at relatively low cost (its just printing an extra piece of cardboard at the end of the day!)
It's not a "may" effect so you have to blow up something, but it also doesn't count mana rocks, so one will lose their Sol Ring or Arcane Signet
Cards from Prismatic Evolution are incredibly highly sought after, and new product is vanishingly rare, with anything that does get put out usually scooped up by scalpers before regular customers can get their hands on it
Especially when it comes to dealing with pesky creatures that stand in the way of victory, or annoying permanents that are neutralizing your plans