Captain America, Super-Soldier Im putting Captain America, Super-Soldier on this list because the decks I play will hate to face this card on the battlefield, except if I have something like Nowhere to Run at the ready
Lands often have no use late game in limited, so sacrificing a couple to give yourself a few extra cards never hurt, especially when the additional costs involved "tap" and not "spend mana"
Second, WotC is printing more and better graveyard answers each set
Also, keep an eye out for cycles like Rock / Paper / Scissors
Its easy to cast with just one blue mana pip and always results either in your opponents conceding or in them being tortured through a much longer game
Sunken Palace I need ways to stock the graveyard before Sunken Palace really excites me, but this offers pretty decent value with a minimal opportunity cost: a tapped Island