Rhystic Study

A very overlooked card that is an EDH staple in my playgroup. If your deck's color ID is blue, you play this card.

this card always becomes the first target of Disenchant/Naturalize or Qasali Pridemage once I play it because it generates sooo much card advantage it's not even funny... well, maybe a little bit funny. Now, run in a multiplayer game and you become public enemy #1. I've been playing with this card long enough now that everyone in my play group never allows me to draw a card, which is okay since I slow the pace of their decks down to a snail's crawl and end up winning anyway.

I cannot even put into words how under-rated this card is. Your opponent is forced to either pay extra for every spell he casts, or to let you have card advantage. Either option is well worth 3 mana.