User blog:DerekBu/Need help with new event

Hello,

I've been playing the new event for a two days now and I got all the new cards and leveled up to star 4 mainly with 2 cards stuck on star 3. But now I could not go any further, playing one battle takes atleast 50-60 energy and boos fight with 100 keys. Could you please kindly comment below to give me some ideas of going further?

Appreciated

The_Ultimate