I'm making these up as I go along sorta, so I'm entirely aware that these cards will likely be unbalanced...
Cursed One
Element: Dark
Type: Creature
Cost: 6 Darkness
Attack/Defense: 1/4
Ability: While you have no cards in your hand, this card deals two poison damage to the opponent. Poison is cumulative.
Note: The poison damage is contact poison, similar to pufferfish.
Blessed One
Element: Light
Type: Creature
Cost: 6 Light
Attack/Defense: 0/4
Ability: Gains +2/+0 for each card in your hand.
The upped versions would probably be something like one more quanta cost for each one, the Cursed One would gain one attack and lose two health, the Blessed one would gain three attack and lose two health. They are both pretty strong cards, but their abilities are also their weaknesses. Dark's ability relies on having no cards in their hand, which means you don't really have any options of things to play, and if you get something in your hand you can't play, such as a spell with nothing to target or if your opponent mutates one of your creatures then reverse times it, you're probably screwed in that strategy. On the other hand, light's ability requires you to have cards in your hand for it to be effective... if your opponent knows this, you'll have a difficult time beating them if you rely on damage alone; not to mention, the card has rather low health, so it's not tough to kill by any means.