Okay, I seem to have spotted some diamonds in there. GJ
Despair: Passing priority won't work, too much coding, unless the card is discarded at random. Still, it's overpowered - you could be instantly killing a creature, or something, and even before the enemy plays it. Can't it just push it to the back of the deck, or something?
Weakness: Good all-around. Sort of like Rain of Fire.
Fear: This is diamond. Great idea, I should be featuring it somewhere.
Dark Pact: The initial cost could be lower, as 3-5 HP is pretty much of a toll for everyturn usage.
Dark Ritual: This is diamond. Opens up lots of strategic possiblities.
Evil Bond: I guess it's alright, but maybe "kill a creature with lesser sum of stats" or "lesser attack" or "something".
Vicious Influence: Darknessemark + This + Quantum Towers + Drain Life = OOOOOOVERPOOOOOOWEEEEERED
Also, suggested before.
Gambler: Gambling is more of Entropy. The effect is very much like Entropy. And it's... fairly costed, I think.
Sinister Sorceror: I'd make it much cheaper. I mean, it is very costly, and all it does is redistribution of stats.