Originally posted by Under the moon
Anti-crystals. Just as a black hole absorbs all matter around it, an anti-crystal or \'black crystal\' would absorb all crystal energy (aka magic) in the immediate area.
And just like if theorised with black holes, once they reach a certain mass, they might form a connection to some other black crystal, so that magic that enters on one side may come out on the other side. Wouldn\'t that be funny? You have this protecxtion crystal, but occasionally it releases random spells of random power tha might hit you, an the probability of this will increase with every use of them and with time (as they constantly absorb the magic of the environment).

Maybe they\'d even explode in a powerful magical burst once they reach a \"critical mass\". Hehe, walking around with a ticking timebomb in your pocket...

Extremely useful things, but not without risk, just as magic itself isn\'t free of risks.