This lets you recur your creatures quite efficiently, especially if you can find a way to protect them
I wont get into the rules minutia here, so just know that planeswalkers are manifestations of popular Magic characters in card form, meant to aid you in your quest to do whatever it is youre doing in-game
Minerva, the Exalted Lightsworn (YCSW-EN008) Estimated Value: ~$25,000 to $50,000 (the Ultra Rare prize version) Why It's Valuable: A Yu-Gi-Oh
It's also worth mentioning that in the late game
The obvious use case is in Lathril, Blade of Elves, as youll be able to attack, get your elf tokens, and then be able to hold up her tap ability from the beginning of the next combat
These can be incorporated into your decks as a subtheme sometimes, or they can occasionally be a main theme in a very particular/lucky draft