Use the number of artifact creatures you control when Robobrain War Mind's second ability resolves, including Robobrain War Mind itself if it's still on the battlefield, to determine the number of energy counters you get
The designers chose to represent this by adding colors to the creature's mana cost
This could be done by including more rare and mythic cards, while keeping prices the same, or by adding more new cards
What sets Rakdos Sacrifice apart from other decks using this engine though is the inclusion of [c]Mayhem Devil[/c]
The Gearhulk Cycle The fifth-scoring spot is, ironically enough a five-card cycle
Its a very simple way of ramping, and while its no good for those aiming for one of every color by turn five, its still an absurdly potent way of gaining mana