As a fan of harrow and a long time TCG player, the mention of a harrow card game developed by the owner of the Merrygleam toy store in Lost Omens: Grand Bazaar caught my eye. I wanted to know more and if anything, actually see a functioning version of the card game developed by someone. So, it was to my delight that Starstone: The Ascension was published a few months later with a fully functioning card game based off the one in Lost Omens: Grand Bazaar.
Starstone: The Ascension itself provides an extension on the lore of the popular card game mentioned offhandedly in Lost Omens: Grand Bazaar that greatly benefits GMs interested in running the plot hooks from the Merrygleam chapter, along with adding in new plot hooks! The new NPCs feel like they're straight out of an episode of Yu-Gi-Oh, especially with the new duel disk style illusodisk magical item that provides vibrant and fun imagery in its description. The mentions of how the church of Nethys, but especially the how the church of Irez, react to this new card game is also a fun addition to the lore I'm happy to see.
As for the game's rules itself, they're simple to understand for any veteran TCG player and ones who've never interacted with the hobby as well! The simplicty of the rules lends itself to the fact that it's primarily stat comparisons between various harrow monsters, with mortal cards being able to band together to also fight the monsters. Event and location cards, along with the charge mechanic also add a bit of complex strategy to an otherwise simplistic rule set that'd get any wizard's mind turning about how to take down their opponent and build their deck. Even then, if the expert rules still need getting used to, there's thankfully an even simpler set of rules also provided!
Additionally, the card sheets provided with the PDF have some adorable hand-drawn art for the cheaper styled cards and are easily printable if so desired to put into homemade packs for your players to open. The addition of transparent cards is also very appreciated for those of us who own a physical harrow deck and don't want to look up the rules mid-game. My sole complaint is that some cards that get stat increases, like the cricket and demon's lantern state they get +1/+0 and +1/+1 respectively, but then state they get +1/+1 and +1/+0 in their reminder text for the keyword associated with the stat increases. This is a minor issue and easy fix when playing, so it doesn't detract too much from the gameplay.
Overall, Startstone: The Ascension is an amazing exploration activity to play during Pathfinder games, especially for games set in Asbalom and I recommend it to anyone who loves harrow or TCGs!