The followups of Phyrexian Dreadnought and other combo pieces like Shallow Grave and Final Fortune make the set extra enticing
While its relatively easy to set up a massive board presence relatively quickly, one board wipe can ruin all of your effort, making it difficult to rebuild
Zul Ashur has two abilities, one is a solid ward effect, one that forces your opponent to lose two life if they want to target her with a spell or ability, which isn't too bad but pretty easy to work around
Whether it is a foil mythic rare, a borderless planeswalker, a full art land, or a common from a bulk lot, Tappr identifies it
Its one of the pillars the game was originally balanced around
The best part of some of these is that they have basic land types, even on dual and triple mana-producing cards