The Ace of Spades is the most overrated card in JJDD. In Ace-High it's untouchable. In JJDD it's the fifth-highest card in the deck. Every night, somebody bids the Ace as a lock, watches it get beaten by a 2♦, and takes a set they didn't see coming.
Four cards beat it
The Big Joker beats it. The Little Joker beats it. The 2 of Diamonds beats it. The 2 of Spades beats it. That's four cards in the deck that can take your Ace, and any of them could be in any opponent's hand.
Empirically, the Ace of Spades wins its book about 75–80% of the time — great odds, but not automatic. Bidding it as a guaranteed book is how bids miss.
How to bid it
Count it as a Likely book, not a Guaranteed one. If it's your only high card, bid conservatively. If it's paired with a Joker or a Power 2, then those are the guaranteed books and the Ace becomes an insurance card.
The situation where the Ace is guaranteed is rare and specific: it's the last card left when only one book remains. Otherwise, respect the four cards above it.
When to play it
Play the Ace early if you want to force out the Power 2s. If a Power 2 hits your Ace, you know the field has one fewer top card and the rest of your spades just got safer.
Play it late if you're saving it as insurance. When there are only two or three books left and the Jokers and Power 2s are all gone, the Ace becomes what it used to be — an unbeatable king of trump.
