I like the groundwork for this character but many of the cards are grossly overpowered. Some examples are:

Love Me!, -10 str for 1 turn and 14 dmg to ALL enemies is stronger than Piercing Wail and Cleave combined, suggest making it only hit one instead of twice unupgraded

Behind the Scene Singing, gives way to much block when upgraded even with its requirement, suggest it be 4 block twice when upgraded

Hide Carefully, same issue with of giving to much block when upgraded, suggest it be 8 block twice when upgraded

Mirror Lake, was able to get duplicate event and then buy mirror from shop in Act 1 for a total of 3, I was able to breeze through the rest with near 800 HP and any damage I took during fights was severely mitigated when my HP reduced at the end of fights, I dont know what can be done to change it but having it be something similar to Buffer rather then large HP scaling.

Ten Instruments scales wildly with its 10 hits, suggest it be 10 dmg 1 hit unupgraded and 10 dmg 2 hits when upgraded with some static block for both

Throwing Apples, its really unintuitive to exhaust skills and power cards for minor dmg, suggest having a base dmg of around 7-9 and for every apple exhausted adds 3-5 dmg

Magic_Beam, is not working properly and not applying Weak, its also WAY to strong for 1 energy.

There doesnt seem to be many forms of Weak or Vulnerable in this character. Suggest Fluttershy cards have more weak appliers and Raidbow Dash have more Vulnerable appliers since it fits their personality's.

yay and Louder!, both seems really weak in dmg and could use plus 1 dmg each. Could also give a temp buff for every time you use yay the next yay does more dmg and can stack, same for Louder! This way there is incentive to put multiples in the deck.

Overall this characher looks to have a lot of promise in the future and I thank you for creating it.