Pick a commander (or, in a 60-card format, a set of colours) and a strategy. The engine builds a full, legal deck from every card in Magic, not just the ones in your binder. Then it opens in the editor for you to grade and tune.
The deck is built inside this card's color identity.
A plan pulls in its payoffs and shifts the deck's land and role targets to match.
A cap on each card, not the deck total, so a budget build can still run thirty cheap staples.