Whenever Sauron attacks, exile target creature card from your graveyard. Create a tapped and attacking token that's a copy of that card, except it's a 3/3 black Wraith with menace. At the beginning of the next end step, exile that token unless Sauron is your Ring-bearer.
Sauron is a mono-black graveyard-value commander that wants to attack every turn, animating creature cards from your graveyard as recurring 3/3 Wraith copies. You self-mill and discard to stock the yard, then swing to generate ETB triggers, bodies, and aristocrat fodder; once the Ring tempts you to Ring-bearer status those tokens stick around permanently for an ever-growing board.
Generates repeated ETB/attack triggers and bodies every combat from cards you've already used
Menace plus the Ring's temptations make Sauron hard to block and reward aggressive attacking
Mono-black gives access to the format's best tutors, recursion, and removal
Loves cheap self-mill/discard, turning a 'cost' into fuel
The copies are exiled at end step until you become Ring-bearer, so early value is fleeting
No evasion outside menace and dies to spot removal, stalling the engine
Single-color access limits answers to artifacts, enchantments, and flyers
Needs both a stocked graveyard and an open attack to do anything