These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Game Breaker: A good way to tell if a card fits this is if they're permanently banned in ELO.
Power Creep, Power Seep: A sad inevitability in a game where new cards periodically come out. It's gotten so bad that not only are some older cards rendered completely obsolete, but a few clans who haven't been updated in a while play with a clear disadvantage altogether.