It doesn't sound like a lot, especially when you have cards like Keeper of the Accord, which can do similar things every turn, but consider this: the land doesn't have to be a basic Plains, and it doesn't have to enter tapped
In a landfall deck, it can easily represent an extra three-to-four power and toughness per creature if you set up a turn for it
Legendary Creature Human Knight Rogue1/1 : Permanents your opponents control lose hexproof, indestructible, protection, shroud, and ward until end of turn
At the beginning of each end step, each opponent loses life equal to the life that player lost this turn
That means this card, at a baseline without ever flipping it, is at worst a Green Grave Titan
Unlike the Masterpiece and Expedition series these will appear in every pack at varying rarities in place of the basic land