Healing can be key to keeping heroes alive
Sheoldred may not be super powerful in constructed (I have faith its good enough for Standard), but it will unleash absolute havoc in Commander
Playing three spells per turn and/or milling yourself is easier in older formats that have access to cantrips like Careful Study and Mental Note
You can work with any budget of mana-base to make use of his first ability
Cards like Vandalblast, By Force, Meltdown, and Bane of Progress can quickly clear away all your opponent's mana rocks, while land destruction cards like Wildfire, Destructive Force, cycled Decree of Annihilation, and Keldon Firebombers remove their lands
P/T Number 316 Language English Legal Formats Brawl, Commander, Competitive Brawl, Historic, Legacy, Modern, Pioneer, Timeless, Vintage Not Legal Formats Alchemy, Pauper, Standard Rulings (2/2/2024) Clue is an artifact type