The most dangerous individual isn't one who just knows how to kill but knows how to heal. Why? Because they can make your suffering last much longer by doing both.
When the universe seemed bent on screwing around with you, the only thing you can do is show the universe the middle finger and push on! Even if that means pushing on in a whole new body.
The ponies tried many ways to convert humanity into ponies, failing countless times. Eventually they simply chose to let the Barrier handle them. Unfortunately though, they are going to meet something that doesn't take too kindly to them.