Like most Magic: The Gathering cards, the value of The Second Doctor depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Doctor Who)
That means she reduces any damage being dealt to her by 1 point per Knight you have on your side, which surely means were going to see some Knight-focused decks in the meta, taking advantage of this excellent ability
The ability to play Shatterskull Smashing as a Red-producing land - possibly untapped and on demand - might win the game
4 Professor Oak Pot Of Greed When your deck already consists of only 20 cards, the ability to draw two is beyond valuable
Nothing at a low mana cost though, like blue, red, and even green have been getting