Hearthstone will be running special rewards for simply logging in March 29th through April 5th. This is a pretty special thing in Hearthstone as most CCGs have gold rewards for coming back every day and to date Hearthstone has been one of the biggest hold outs. That said for the next 8 days that changes so you should log in each day to get the 4 packs, 100 gold, 100 dust and a special Golden Volcanosaur card from the upcoming Ungoro expansion.