The legend comes first
Your legend is not just a strong card. It is a constraint system. Every legend has a signature card that grants access to specific domains. This means the cards you can play are defined by your legend before you add a single card. If you pick LeBlanc, you play in LeBlanc is unlocked domains. If you pick Master Yi, you play in Yi is unlocked domains. This is not optional. It is the first rule of legal deckbuilding. Before you add any card, know which domains your legend grants.
Domains are a gate, not a suggestion
Riftbound uses domain pairs as a deckbuilding gate. You can only play cards whose domains match at least one of your legend is unlocked domains. Two legends in the same domain pair feel similar but play differently. The legend is text, stats, and signature mechanic are what change everything. When building, use the Cards page domain filter to show only legal cards for your pair. This removes illegal cards from your search before you open a single card text.
The 61-card minimum
Riftbound decks have a minimum of 61 cards. Going above 61 is legal but statistically worse. Every extra card dilutes your chances of drawing the cards you need. The rune deck is separate and has its own minimum, usually around 20 cards. The rune deck is your consistency engine — cards in it are not in play until you channel them. A common beginner mistake is loading the main deck with rune-specific cards instead of cards that actually affect the board.
Building from scratch vs. copying a list
If you build from scratch, start with your legend is signature card and build the core around it. Identify three card roles: early stabilization, midgame pressure, late-game finish. Fill each role with cards from your domain pair before looking outside it. If you copy a list, use the domain filter to verify every card is legal — legends can shift domain access between patches.