Based on the episode of the same name where Twilight had several screws come loose. The card's info says:
RB10-EN066:
Lesson Zero
Normal Spell
Tribute 1 "My Little Pony Knowledgeable Twilight Sparkle" or "My Little Pony Princess Twilight Sparkle" you control with 0 ATK, then apply this effect based on the Tributed monster's name.
- "My Little Pony Knowledgeable Twilight Sparkle": Special Summon 1 "My Little Pony" monster from your hand with DEF equal or less than Tributed monster's DEF.
- "My Little Pony Princess Twilight Sparkle": Special Summon 1 "My Little Pony" monster from your hand or Deck.
Rainbow Rare