The Infernal and Dark Pact seem quite good. Assuming the infernal kills anything it gets into combat with (which it probably will), the 1-card loss a turn isn't a big deal. If the infernal dies, you don't need to worry about the discard. Dark Pact is pretty ridiculous as far as card drawing goes. I mean, I hope they know what they're doing because if a card like that showed up in Magic it would get banned before it even got to the printers.
Of course, card drawing is handled differently in this game it seems... a land that you can pay three mana to draw a card once in Magic would also be way overpowered, but look at the quests in this game.