Hi! Welcome to the Forum and to Magic
Mikuyume has made some excellent suggestions and by making those
simple changes, the deck should play much more consistently.
I did want to bring
Endbringer to your attention. The Diamond symbol means it must be paid with colorless mana and not colored mana. As the deck stands, the only purely colorless source is
Drownyard Temple, which means in order to play
Endbringer, you have to have that land. The good news is, as Mikuyume said, you're going to need more like 23 land for a control deck, so you could add something like
Warped Landscape or a couple
Wastes (which you could find with
Traveler's Amulet) to get the colorless count up.
Also, another cheap card that's great in control decks is
Gurmag Angler. He lets you use your graveyard as a resource to and combos beautifully with
Sorin, Grim Nemesis. However, since he requires so much delve to work, running more than 2 of them would be risky.
Murderous Cut is equally cheap and follows the same Delve theme.
I hope you found this helpful. Good luck and Happy Hunting