In Route 217 (the snowy route heading to Snowpoint City), there are two houses. In the first house, a hiker will give you an Icicle Plate if you have taken HM 08: Rock Climb from behind his house. In the second house, a lady will give you a Spell Tag. Enter the second house and talk to the lady to get a Spell Tag. Then, go outside and enter the house again. The woman will no longer be there.
