The Herrlof deck consists of 42 cards:
- 1-9 in 4 suits
- 3 Valknut (no suit)
- 3 Hagalaz (no suit)
Each hand, players are dealt 15 cards, and one card is dealt face up to the table. The suit of the table card becomes the current trump (Valknut or Hagalaz mean there is no trump suit.)
The game is played over several hands. Players secretly bid how many tricks they think they'll win. Points are awarded for correct bids, as well as tricks won. If a player has 50 or more points at the end of a hand, the game is over and the player with the highest score wins. Ties are broken by most correct bids throughout the game.
Opening play alternates between hands. For each trick, the lead player may play any card. If the card is suited, their opponent must follow suit if able. If the opponent can not follow suit, they may play a non-suited card. However, Valknut and Hagalaz cards may be played instead, regardless if the player has a suited card to play (see their effects below).
The highest card of the lead suit wins the trick unless a card of the trump suit is played. Then the highest trump suited card wins the trick. The winner of the trick leads the next trick except where noted below.
Some cards have special abilities:
- 1: If you win a trick with a 1, you may steal a trick (point) from their opponent. The stolen point must have been earned in that hand.
- 3: When you play a 3, you may immediately draw a card from the deck of undealt cards, then return a card to the bottom of the deck.
- 6: If you win a trick with a 6, you may steal a random card from your opponents hand, then return any card back to their hand.
- 9: If you win a trick with a 9, your opponent gets to lead the next trick.
- Valknut: Destroys the trick it is played in (no point awarded). If two are played in the same trick, the trump is replaced with the top card of the deck.
- Hagalaz: The lowest card. It loses all tricks, but also gives you the lead for the following trick. If two are played, the second one has this effect.
After all cards have been played points for the hand are awarded as follows:
- 1 point per trick won
- 5 points for winning exactly 3 or 4 tricks
- 10 points for bidding correctly
An early draft of the rules provided the 5 point bonus to hands where 5 tricks are won (in addition to 3 and 4). This has been provided as an option, but is not the intended design of the publishers. It is provided for players who may have played this way previously.
A 3-player variant is supported, but not recommended. The rules are altered as follows:
- Players are dealt 11 cards per hand.
- The game ends at 40 points instead of 50.
- No 5-point bonuses are awarded.
- You may choose which opponent to use special abilities on.
- The 9's ability gives the lead to the player after the trick winner.