good fiend cards yugioh Fiendsmith's Lacrima - Yu-Gi-Oh! Card Database player and collector. Fiend Griefing - Tactical Masters

Several factors influence Base card values: card condition (mint cards worth 3-5x more), rarity (holographic and rare cards command higher prices), first edition status, PSA/BGS grading scores, and market demand for specific Pokemon

Auction prices and population reports for Pokmon promo cards

While it does not deal an immediate 20 damage the same way Rocky Helmet does, Poison's accumulative damage in between multiple turns is more significant than Rocky Helmet's 20 damage

Zygarde-EX has the (potentially devastating) Power Memory Item card, and while its not as good as Genesect-EXs G Booster, its still able to OHKO most Pokemon

Source:

At its heart, [Fraens] card scanner is all about paper handling, which is always an engineering task fraught with peril