It helps you smooth out your mana and when it dies, you draw a card
This has proven to be a highly effective deterrent, reforming those who are ready to never hear another one of his lectures again
A deck aiming for that would have a solid 13 plays on turn one, with 10+ being acceptable, in order to blitz on turn 3
In Commander and other multiplayer formats, I think Righteous Fury is the better card of these two, and it's in some of my Commander builds right now
There is the risk that some decks out there don't have any spells they won't be able to cast, but the loss in such a case is the mana required to make him work more than the opportunity cost of a larger creature
Donquixote Doflamingo is the extravagant and flamboyant captain of the Donquixote Pirates, and his One Piece Parallel Leader card reflects those qualities in spades