Instead of just limiting a card to only one copy per deck, they forbid the usage of certain cards entirely
While its a level four monster with 1800 attack and 400 defense, in order to attack you have to tribute a water type monster, attacking three times in each battle phase
Returning Keyword Ability: Saddle Not everyone in this race uses a mechanical mode of transportation
C Common Thunder Hand X LIGHT Level 4 [ ThunderEffect ] ATK 1600 DEF 1600 If a face-up monster(s) you control with 1600 original ATK or DEF is destroyed by battle or an opponent's card effect and sent to the GY, while this card is in your hand or GY: You can Special Summon this card (but banish it when it leaves the field), and if you do, destroy 1 card your opponent controls
Actually, there's no ethical or acceptable reason to make "proxies" to pass the light test, bend test, and other well-known tests to weed out fake cards because there's no ethical or acceptable use of proxies that requires the proxy to be as similar to a real card as possiblea Sharpie on a basic Island does the job just as well and without any of the legal and moral issues