A Zanderein Crystal is the opposite of an Azerdain Crystal, where a Azerdain crystal empowers and enhances spells a Zanderein crystal drains them. A Zanderein crystal sucks in light where an Azerdain emits a dim glow. A Zanderein crystal is paradoxical in nature due to the fact that it rejects magic but is itself a magical item. 

1 Charge:

 - decrese spell strength
 - slower casting 

2 Charges:
 - decrese eell ranged

 - decrese spell duration

 - target fewer creatures

3 Charges:
 - stop spell from casting

The size of the crystal also affects the strength of the crystals effects. This is currently up to the DM but generally the larger the crystal the more powerful.