The Abyss is one of the most powerful cards from Legends and it is the bane of most creature decks in the format. But here's the thing, The Abyss has a small "loop hole" and that is what this deck is built around. Usually you only put The Abyss in a deck completely without creatures, but this deck does the exact opposite and plays a whole bunch of creatures.
The Abyss’ ”loop hole” is that it actually doesn't kill all creatures, instead it leaves artifact creatures alone. Therefore, this deck plays 2 - 4 The Abyss to kill all of the opponent's creatures, and then it utilizes Su-Chi, Juggernaut and other artifact creatures that don’t care about The Abyss to smash the opponent's face.
That is the foundation of this deck and what other cards to fill the deck whit is completely up to you. A couple of examples are Sinkholes, Underworld Dreams, blue splash for power or maybe a red splash for Lightning Bolts and other burn spell.