Be'lakor, the Dark Master As someone who played a lot of Warhammer 40k in the 90s before I discovered Magic and had a different giant hole into which to funnel my cash, I respect that the best demon commander is from 40k: Be'lakor, the Dark Master
Most notably, after you get four cards in the Lost Zone, you can attack for free with Cramorant [Lost Origin], seven allows you to accelerate Energy with Mirage Gate [Lost Origin], and ten cards allows you to spread damage counters with Sableye [Lost Origin]
But why is this the case
A 2/5 for 4 mana is already a great value, but combine that with flying, toxic, vigilance, and corrupted, and you have a war crime
Im most excited to slot this into Shanna, Purifying Blade, but it can honestly fit in a myriad of builds