Each level has three stars that can be earned. The stars represent your Skylanders. If all of your Skylanders are not defeated in battle, you will earn all the stars. Earning all three stars on a level will reward you with bonus coins. Earn all the stars in an entire realm to get bonuses such as new card packs and more coins. When an ally gets too low in health, switch them out for another. Be careful of spell cards that can attack your allies that are being held in reserve.