@Delta Brony
You mean that she incidentally revived Midnight Sparkle and let her possessed the Princess of Friendship just like what she did to Sci Twi. Then maybe after Daydream Shimmer have defeat Midnight Sparkle, he essence was drained in the remains of Sci Twi’s shattered amulet before it was restored by Princess Dark Matter. And when you defeated Midnight (who now goes by the name of Princess Midnight Sparkle), she eventually ended up in Sci Twi’s mind when she begins to haunt Sci Twi.

Unlimited POWER

@Spiritus Arcane  
On the one hand, she didn’t know it was a magic-draining device at the time.
 
On the other hand, wearing an unidentified alien artifact is itself a bad idea.

Lesson one on why it’s a bad idea to wear a magic draining device when you yourself are a magic creature.

After Twilight read Sunset Shimmer’s message, the device starts to light up on its own. “What’s going on?”, Twilight said. The device began opening up, revealing the magic that is inside of it. Twilight looked down at it, and then the device began to light up once more. Then, the device started sucking out Twilight’s magic. The princess of friendship struggled, and screamed as she is getting drained by the device. “Nooooo!! Aaaaahhh!!”, Twilight wailed, but it couldn’t stop. The magic of friendship that was inside of Twilight was fully extracted and sealed into the device, causing the magic from Midnight Sparkle to take over her body.

@Millennial Dan  
Hehehe! X3 Your continual tutorship has been most invaluable!

**snaps suspenders**
 
Taught her everything she knows.