I chose that because I needed something that protects well enough for one or two turns at most. Once four or so novas are out, it buys just enough time, while being affordable, the light, fire, water mana is used by the combo/delay after that, you need a shield, with the extra quantum there, it works well enough.
Although a Phase shield would probably work very well also, if it's stolen, that's big trouble for the deck, where if the Dis is stolen, then against some, you should be able to eliminate all their quanta still buying you time in another respect.