If you're in the middle of a duel and you pull off a nice play, gauge the reaction of your friend
Or, they can go for something different like Alluring Mirror Split (which will special summon a Harpie monster card from the deck if one is destroyed by battle), Harpie's Feather Rest (which allows the player to shuffle three Harpie monster cards from the graveyard into the deck and draw two cards), or even Harpie's Hunting Ground as mentioned earlier
As long as this Pokmon is on your Bench, your Zygardes and Zygarde-GXs attacks do 20 more damage to your opponents Active Pokmon (before applying Weakness and Resistance)
If that card is yellow, trigger Recovery +1 (Deck)
The Mana Rig, Alquist Proft, Master Sleuth, Nin, the Pain Artist, Tameshi, Reality Architect, and many others can really make use of this discounted double-activation sweet spot
And I dont mean the holo in the very first picture, which makes it appear yellow/orange (which is also cool btw, FWIW)