While the deck is already good, Mardu (red/white/black) has plenty of useful support cards for the strategy that make it a great base deck to upgrade over time
Brawl Legal Vintage Legal Timeless Legal Commander Legal Pauper Not Legal Oathbreaker Legal Penny Legal Toolbox Notes and Rules Information for Fell the Mighty: Use the power of the target creature as Fell the Mighty resolves to determine which creatures are destroyed
If you care about fixing for multiple colors and getting elementals into play, or want an extra creature lying around, you can probably play Llanowar Loamspeaker
Timing restrictions based on the cards type are ignored
If you send a monster that is LIGHT from his original attribute DARK to his GY with the effect of Subterror Succession, you can add his LIGHT monster from the Deck to your hand
This multi-creature lord is a fun build-around, especially in Commander when you can technically turn it into a second commander via its companion ability