Nico's Hyper is Miracle Walker. When used, the player will discard all cards in their hand, and replace them with an amount of random Hyper cards equal to the number of cards that were discarded. These Hyper cards will be randomly selected, and can be any Hyper in the game, barring Hypers that can't be normally obtained in the hand. The player is then allowed to play 1 additional card on the same turn.
Despite the card's wording, this Hyper does not transform cards, instead discarding them before generating random Hypers equal to the amount of discarded cards. Due to this, when any of the generated Hyper cards are used or discarded, they are removed from the game rather than being sent to the discard pile.
Miracle Walker is a very luck-based Hyper, depending on chance to get a beneficial Hyper for the current situation. The best time to use it would be when the player has a full hand with >4 cards to get the most out of the conversion. There is not much risk to playing this card if the player is Nico, as any potentially detrimental Gift-type Hyper cards will not apply their effect due her passive, and will instead allow Nico to gain more stars. However, this risk is very present if the player is any other character.
This Hyper allows Nico to be very aggressive and scale up incredibly quickly with powerful effects and stats increase backing her up. Getting cards such aswill allow her to enter combat and have a higher chance to KO enemies, while others like let her come out of battles generally unscathed. Other supportive cards like or can let the player amass a great amount of stars or lower enemy HP safely. The player can also easily trigger combos between different Hypers, such as activating then in battle to guarantee a natural 10 roll.
The main downside of this hyper is its randomness. Despite the generally good cards that can be drawn and potential powerful combos, many times they won't be acquired in the appropriate situation or they won't be useful () or hinder Nico too much ( ). It's generally better to get a full hand of cards before using the Hyper in order to get more chances for a good Hyper, which can be difficult to achieve on maps with panels too far apart.