In UFS, a negative playing experience (NPE, for short) is exactly what it sounds like. In essence, any deck could be a negative playing experience for a new player, while some card combinations are often times so overpowered they are considered NPE.
There really is no way to list examples of NPE, because the meta varies too often. Whenever there's NPE, usually in a later set answers are released. However, to list just one example, promo Rose (***Rose***) was often considered NPE if used in a control deck. Her ability to choose which card is used for the check can not only make your opponent fail critical checks, but could intentionally force them to lose a card they need in a control check due to ***Rose***'s complete control over control checks. It's this feeling of not being able to do anything about it that often causes NPE.
The Paradigm of Preventing NPEEdit
There are often ways to stop NPE, but more so often, the answers are so specific and situational that not many will consider to run them. Thus, NPE will always exist.