Effect updates and description changes can be seen here.

Snow Storm is a Patience deck specific effect card. Since Beta 7.4, it turns all monsters on the board, including your own, into either Ice, Ice Cap or Snowman randomly.

This is very useful if you want to get rid of powerful cards of the opponent, and useless cards of your own. If you gained an Ice Cap out of it, it can attack right away. You can use this to either attack directly (if the opponent didn't get an Ice) or kill it in order to place something more powerful or with a good ability, such as Pyrope, Trader Temmie, Gaster or Sans.