Fun Fails to Exceed Anti-Fun
This is where the 'anti-fun' created on your opponents by your use of a mechanic is greater than your fun in using the mechanic. Dark Binding is VERY favorable on this measurement, because opponents get clutch dodges just like you get clutch hits. On the other hand, a strong mana burn is NOT desirable -- if you drain someone to 0 you feel kinda good, and they feel TERRIBLE -- so the anti-fun is exceeded by the fun. This is important because the goal of the game is for players to have fun, so designers should seek abilities that result in a net increase of fun in the game. Basic design theory, yes?