Diversion is, in my opinion, the 6th best card-denial skill in the game (following, in order: Mage Hunter, Cyborg, Champion of Light, Champion of Water, and Find A Weakness), and even though I rank it as such, does not limit its power. The reason I feel it isn't the best is because it can target only one card. That one card, however, may be the most important part of the opponent's deck! I feel that it is a fine skill, if not slightly above average in power level, considering it is a Tier 1 skill.
Entropy has several confusion abilities that are meant to wear and tear at the opponent during and before battle. I feel that this give them a unique advantage. Whereas things like Fire, Darkness, and some others have abilities that affect the gameplay directly, Entropy modifies the ability of the player to use his deck effectively and efficiently. This is a good trait, and I also enjoy the teleportation ability they possess, even if there's a chance one will simply land on the hex next to them, at the cost of a relic.