Generally you want to make sure you have a two or three-color identity for a theme like this, and remember that the majority of your good enablers will be in Grixis colors: Brallin, Skyshark Rider plus Shabraz, the Skyshark Raffine, Scheming Seer Chainer, Nightmare Adept Rielle, the Everwise Soul of Windgrace Amber Gristle OMaul plus Agent of the Shadow Thieves (or Criminal Past) Slogurk, the Overslime Despite their contrarian approach to the Commander metagame, discard decks are capable of some truly disgusting lines and offer a huge range for individual expression
Meanwhile, Umara Wizard isn't a horrible creature since it is big enough to take down quite a few Commander-playable creatures in combat and the ability to gain flying is relevant
Heliod, the Radiant Dawn is a very straightforward commander in this way, costing a fairly cheap four mana to transform him, or three mana and two life, to compleat the poor god, turning him into a twisted, Phyrexianized version of himself
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