Rank-Up-Magic Nightmare Force

-Card Info-
Name: Rank-Up-Magic Nightmare Force
Type: Normal Spell Card
Rarity: Ultra Rare
Effect: Target 1 Xyz Monster you control; Special Summon from your Extra Deck, 1 Dark-Attribute Xyz monster that is 1 Rank higher than that monster you control, by using it as the Xyz Material. (This Special Summon is treated as an Xyz Summon. Xyz Materials attached to that target also become Xyz Materials on the Summoned monster.) If your opponent controls a Synchro Monster, you can activate this set card during your opponent's turn (this is a Quick Effect).

First things first, it can rank up an Xyz Monster into ANY Dark-Attribute Xyz Monster, that is 1 higher then the original. Its final effect is designed to be a counter to Princess Celestia. When her effect is activated, you can use this card in response to make her effect fail and get a monster that Celestia is not strong enough to get over herself.