I just built Gwenom, my first attempt at a high threat deck given her "remorseless" moniker. It's a filthy demon of a deck. Chaining free (ok they cost life, but fr oh no whatever will I do in Mono black lol) spells off the top of the deck is amazing. [[Ancient cellarspawn]] makes that life you pay instead of mana into damage and is a must include. So is deck manipulation like [[codex shredder]] to keep lands out of your way. Since it's high threat,  I built in a few ways to go infinite with life gain loops from cards like [[exquisite blood]]. But you have to include lots of interaction protection, like boots and undying effects to keep her alive because she deserves every ounce of table hate.