I was thinking, and please bear in mind that this is only an idea, and is not thought through much, so it's not really complete.
How about a card, permanent (poss. weapon) that can be charged, for say 3 quanta, to do extra damage. However, as this card is charged, it also becomes unstable. Every time it is charged, it gains 10% chance to destroy itself. So, you have to decide 'Do I want extra damage, or a card that is more likely to stay usable? I'm not too sure where this would fit, possibly in entropy.