More commonly, you see Overlord of the Balemurk in Pioneers Mardu Greasefang, which does a rather stellar job of throwing key cards such as Parhelion II and Skysovereign, Consul Flagship into the graveyard that can re-enter play with Greasefang, Okiba Bosss trigger at the beginning of combat
[spoiler="Fire Maiden"][/spoiler] Gains 100 ATK and DEF points for each fire attribute monster in the Graveyard
This was the foundation of the map work
When you choose a deck, all 20 cards within it are added permanently to your collection , and can be used freely - meaning that you can put them in decks you make yourself so if you have all the cards in the Clodsire ex deck, it means there's no point in choosing that one, as you'll only get duplicates
Flavor wise, he is set out to make people enemies of each other, so making the Devils deal damage to creatures wouldn't make sense anymore
His "mandatory delve two" resource consumption makes him well balanced and interesting