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: Super Sonic. There's a reason he's an unlockable.
Sonic's special move can sometimes be this; if he gets the same number twice he can move double the spaces. IE, if he got two 2s, on the second turn he could move four spaces.
Which sometimes turns into a self-imposed Stop Helping Me!, because if you're not aware of Sonic's special move at all times, you can overshoot where you're trying to go, since with the double-move you must move the required double amount of spaces.
Several Forcejewels are game breakers, such as Stopnite, which blocks off a space for 3 turns, Barrier Amber, which prevents anyone from passing you for 5 turns, and Curse Opal, which can randomly stop a player from moving for up to 5 turns.