Some of the best includes for a Charioteer deck are any creatures with deathtouch and more than a point of power and toughness suddenly thats a guaranteed dead blocker and damage, however small, squeaking by
Its a sacrifice outlet that will give you back the mana it took to cast it the first couple of uses
If you like to use your graveyard as a toolbox, filled with creatures that act both as finishers and value pieces, this is the deck for you
Green has the most powerful ramp spells, while red and black have fast and situational ramp spells, but white and blue are often left out in the cold
If you have only madness cards, the mana cost of your spells will be too high and you might have a very slow and not powerful game, If you only have discard enablers, you might create card disadvantage and finally having cards with no effect at all
Likely 50% or well below the value of what you have