Have you opened any rare Legendary or Enchanted cards yet
Normally, a combo of these 2 cards will prevent an opponent from attacking, even if they discard in accordance with the effect of Gravekeeper's Servant as Banisher of the Light will force the discarded cards to be banished instead of sent to the graveyard
For the uninitiated, EDH stands for Elder Dragon Highlander format, also known as Commander format
Alongside Pidgeot ex, with which it has synergy, these decks did very well
At a cost of seven Ink, it isnt cheap to play, but if you have a character that costs seven or more on the field, you can tap it to play Be Prepared without paying its Ink cost
Despite this blue has good ways to regain lost card advantage and far fewer good ways to gain tempo making this a good filler card to help all manner of quirky blue dork decks