The Illustrious 18: The Blackjack Deviations Worth Learning

Basic strategy is the mathematically correct way to play every hand — against a neutral shoe. Card counting tells you when the shoe stops being neutral. The Illustrious 18 is the classic list of the eighteen most valuable strategy deviations: specific hands where, at a specific true count, the correct play flips away from the basic strategy chart.

What index plays are

An index play (also called a deviation) pairs a hand with a true-count number. When the count reaches that number, you switch from the book play to the deviation. Below it, you play the basic strategy chart exactly as written.

The logic is simple. Basic strategy assumes the remaining cards are a roughly even mix. When the Hi-Lo count climbs, the shoe is rich in tens and aces; when it falls, it is rich in small cards. For most hands, that shift changes nothing. For a handful of borderline hands, it changes everything — and those borderline hands are the Illustrious 18.

Deviations are the second layer of edge

Most of a counter's profit comes from the bet ramp: small bets in bad counts, big bets in good ones. Each true count point is worth roughly a 0.5% edge shift, which is how a proper spread on a good 3:2 shoe game turns basic strategy's roughly -0.5% into somewhere around +0.5% to +1.5% for the player. (Never at a 6:5 table — that payout alone adds about 1.4% to the house edge and makes counting effectively worthless.)

Deviations stack on top of that. The ramp decides how much you bet; index plays squeeze extra value out of how you play the hands you are dealt — precisely in the counts where your biggest bets are already on the table. If the ramp is new to you, read the true count guide first: every index below is a true count, not a running count.

The full Illustrious 18

Standard Hi-Lo indexes in the common six-deck H17 context, listed roughly in order of value:

A note on splitting tens: yes, the list really does break up a made 20 against a 5 or 6 at high counts. It is also the fastest way to get backed off, so many counters skip those two on purpose. The math and the practical decision are separate questions.

How to read "stand at +4"

The rule: take the deviation when the true count is at or above the index. "15 vs 10, stand at +4" means at TC +4 or higher you stand; below +4 you hit, exactly as the chart says.

Negative indexes read the same way — they just bite in the other direction. "13 vs 2, stand at -1" means stand at -1 or above, which covers every neutral and positive count, so it matches basic strategy almost all the time. The deviation only appears when the count drops below -1 and you hit instead. All four negative-index plays are hands where basic strategy stands and a bad enough count talks you out of it.

One housekeeping point: pick a rounding convention and keep it. Our trainer floors the true count for the bet ramp; whatever you use, apply it consistently. And if the Hi-Lo values themselves are still shaky (2–6 = +1; 7, 8, 9 = 0; tens and aces = -1), lock those down with the Hi-Lo system guide before adding indexes.

The big four

Insurance at +3. The most valuable play on the list. Insurance is normally a losing side bet — basic strategy says never take it. At TC +3 or higher the shoe is dense enough in tens that it flips profitable, and because it is offered on every hand against an ace, the situation comes up constantly.

16 vs 10, stand at 0. The most frequent hand on the list. At TC 0 or anything positive, stand; in negative counts, hit. The trigger is easy: any non-negative count means stand.

15 vs 10, stand at +4. Same idea one notch later — the ten-rich shoe makes the dealer's pat hands and your bust risk both worse, so standing wins the race at +4.

12 vs 3, stand at +2. Basic strategy hits 12 against a 3. At +2 the shoe holds enough tens that the hit busts too often, and standing takes over.

How to practice them

Do not memorize all eighteen at once. Learn insurance and 16 vs 10 first: one is the biggest earner, the other is the most common, and both have dead-simple triggers. Play with only those two until they are automatic.

Then add 15 vs 10 and 12 vs 3 to complete the big four, and work down the table from there. The plays are listed in order of value, so every row you add matters less than the one before it. Remember that deviations pay off in the same high counts where your biggest bets are out — which is exactly when variance is largest, so size your bankroll for the swings.

Watch each deviation appear live

The fastest way to internalize indexes is to see them happen. Our free card counting trainer computes exact-composition EV on every decision in real time, so you can watch standing on 16 vs 10 overtake hitting as the count crosses zero, or insurance turn positive as the true count hits +3. It also runs million-hand simulations showing the ramp bettor beating the flat bettor over the long run. All of this is pure skill: counting with your brain is legal everywhere in the US, as covered in is card counting illegal.

Educational content only. Practice with fictional chips on our free trainer — no real money, no casino affiliation. 18+.

Frequently asked questions

What is the Illustrious 18 in blackjack?

The Illustrious 18 is the classic list of the eighteen most valuable card-counting deviations from basic strategy. Each entry pairs a specific hand with a true-count index — when the count reaches that number, the correct play changes, such as standing on 16 vs 10 at a true count of 0 or higher. Together they add extra EV on top of the profit a counter already makes from raising bets in good counts.

Do I need to learn all 18 deviations?

No. The list is ordered by value, so the top plays carry most of the weight. Start with insurance at +3 and 16 vs 10 at 0, then add 15 vs 10 at +4 and 12 vs 3 at +2 to complete the big four. The remaining plays each add progressively less, so learn them only after the big four are automatic.

What does an index like "stand at +4" mean?

It means you take the deviation when the true count is at or above the index, and follow basic strategy below it. For 15 vs 10 with an index of +4, you stand at true count +4 or higher and hit below that. Negative indexes work the same way: "stand at -1" means stand at -1 or above and hit only when the count falls below -1.

Is insurance ever a good bet in blackjack?

For a basic strategy player, no — insurance is a losing side bet and should always be declined. For a Hi-Lo card counter it becomes profitable at a true count of +3 or higher, because the shoe is rich enough in tens that the dealer completes blackjack often enough to make the 2:1 payout worthwhile. It is the single most valuable play in the Illustrious 18.