Here is what the announcement says:
1. Do not rush to purchase your items, carefully pick the luck + additional options (skill+luck+7%hp...) + excellent options. And do not pick 4-6 options if you intend to trade them around
2. Do not store any season1 items when you purchasing items from web-shop
3. Do not leave your vault open when you are purchasing
4. Don't choose the last 2 options in purchasing 3rd wings,only choose first 4 options
5. Don't buy season 4 items in webshop and expect them to come with sockets. All of the webshop season 4 items don't have sockets
Please pay attention to this simple lines because in case you don't respect them and you buy the wrong item your credits might not be refunded.
Also, in order to stay up to date with possible changes regularly check this thread and the announcement section.