I can explain why the resemblance to King Sombra xD
I have created my own timeline of what happened in the Crystal Kingdom, how scary King Sombra was the war crimes he commited, resulting in two illegitimate daughters. One of them is Thunder Scribbles, King Sombra broke her horn when found about her existance. Mushrooms (pegasus) was never found by King Sombra since her Mother scaped to the Snow Mountains and died. Mushrooms was raised by snow wolves, which is why she doesn’t know how to fly, talk or basic math.