There are currently 25 different types in the game, including Dragon, Sea Serpent, Beast, Warrior, Beast Warrior, Spellcaster, Psychic, Zombie, and more
These are legendary enchantments that can reside in the command zone and be played in the same way you play a regular commander
Lillie is going to stretch that to three, and thats not including healing abilities from Potion and Giant Cape, which can be played on the same turn
The reasoning for this is because you want your deck to follow a theme, an overall goal for you to achieve with your deck, and there's a limit to how many cards will help you achieve that goal in a timely matter
One of the joys of being a Magic designer is being able to take cards you enjoy and make new versions of them
However, while Yugi often had to figure out how to use what the Heart of the Cards gave him, Yuma's Shining Draw requires much less skill to use, requiring him to improve less when he uses it