I just have a few pointers;
Alot of the cards have pretty crazy effects - much crazyer than what would be on a regular card for Yu-Gi-Oh - things such as both players taking some damage wouldnt regularly happen but is cool however so i would keep that. The crazyer things are Selecting any card from the other players deck and taking it, and having an effect triggered on guessing numbers (generally its a coin flip or a dice on rarer occasions)
Generally, cards with effects wouldnt have descriptions as it can be hard to tell what is effect and what is just a description.
Damage in Yu-Gi-Oh is almost always rounded to hundreds.
Alot of your cards deal small ammounts of damage such as 100-300 ish. In a game of Yu-Gi-Oh you have 8000 health, so these small numbers dont mean much to the overall game.
The rankings on cards (their stars) on your cards seem pretty inconsequential to the cards effect / stats. Higher stared creatures would have better effects as they are harder to summon.
You dont summon spells / traps, only monsters, you activate spells / traps.
The cards are incredibly cool, and some of those above are nitpicks. Feel free to not do any of these things, as the cards dont need to be balanced (as if there was balance in Yu-Gi-Oh anyways) or 'correct' really, you are just making them for fun - so stick to that!
