Im including some other cards that play nicely with legendary permanents: 6
The Seventh Doctor is far more complicated, but thats perfect for that particular incarnation of The Doctor
It is not difficult to be the monarch because the back side Starscream, Seeker Leader will make you one the moment you deal combat damage to an opponent, and I absolutely want to watch someone pull off a Peer into the Abyss in the second main phase after Starscream, Seeker Leader is converted into Starscream, Power Hungry
It counts the deck modulo the number of piles, and helps makes sure the player hasn't lost a card
Quick Draw probably has the best base for a competitive deck, given its emphasis on cheap, interactive spells and potent combo finishers
#6 Tlincalli Hunter Tlincalli Hunter is an interesting card