She can defend, draw, heal, remove cards from Life on her own terms, and grind through long games while still having enough pressure to punish opponents who give her too much time
Add to that the second most potent card draw engine in Underworld Connections (second only to Jace, Architect of Thought into Sphinxs Revelation) and there are some rich incentives to cast black cards
Spellslinger decks can probably do better, but I wouldnt be surprised to see this pop up in the 99 of some lists
Since Toon Black Luster Soldier's Special Summoning condition involves Tributing other Toon monsters from its owner's hand or field, putting this card on the board is almost always at least a -1 in card economy
This great proliferate card is fantastic in superfriends or counter decks that want to double up on their value whenever lands hit the battlefield
Zerodown cobbled together a quick list of cards centered around the premiere combo enablers