Vintage Scrabble board game h power tiles

There are 12 colored tiles with stars on them in addition to the regular set of 100. According to the box, you can use them in 3 different ways: -As a blank tile, but it scores 3 points instead of zero. -As a "blocker"- to keep players from playing on a space. -As a "free exchange"- you can exchange tiles, but it doesn't cost you your turn to do so.