The Queen, Commanding Presence and Four Dozen Eggs can turn your Seven Dwarfs army into a formidable battalion that will often catch your opponent by surprise
Gisela, Blade of Goldnight, Ojer Axonil, Deepest Might, and Torbran, Thane of Red Fell unconditionally increase the damage of your burn spells, as do other damage doublers and damage increasers
You can transform it when it attacks, and that also gives your other legendary creatures a small Overrun effect
TheChirurgeon: The Offspring decision here is so incredibly interesting - it's got huge potential upside, especially given you're likely to pull more lands, but you could end up eating a lot of life loss really quickly this way and accidentally drawing yourself out of games
The Marvel Super Heroes Scene Box: Villains Unleashed is a good way to put this on display, because when villains work together, bad things happen
And yes, for those who are unsure, that is Liliana in the art getting her "contract" (the full-body tattoos)