The Ravnica block was notable for being the launching platform for hybrid cards. Hybrid is a variation of the gold card which makes it easier to cast since the mana symbols are interchangeable. For example the card had two blue and white mana symbols, you could choose either to pay two white mana, two blue mana or a combination of both mana types.
The Ravnica block was also famous for its series of guildmages which had two abilities. A two to cast creature for 2/2 was good enough but add two abilities and it becomes great. This particular card has the ability to single handedly shut down the opposing army as long as you have enough mana to do it. It not only shuts down the attack of the creatures but their activated abilities as well. This fits well in a blue / white control deck.
This card version is a special release version and is not available in booster packs. $2.00 for this card is a good deal. This is good for avid collectors.