Any time a dragon enters the battlefield, you get a second copy as a token
Well, that and the time to be played more than once as far as the speed of older formats is concerned
You can also use Dark Rituals 3 mana by casting Demonic Tutor to find your best card and following up with Entomb for one of your cards to go into the graveyard from later casting with Anrakyr the Traveller or Blood on the Snow
It changes only the value of the combat damage it assigns
You dont need to have max speed to get value from it, but the faster you go, the better it gets by granting you access to more card draw
Slingin Spikes In cEDH With that draw ability alone, Shadow the Hedgehog makes a great Commander of, or addition to, Rakdos Aristocrats decks in MTG