Strategy · Index Plays

The Illustrious 18: Blackjack Deviations by True Count

By VectorLogic · Updated October 2026

The Illustrious 18 are the first deviations most card counters learn: insurance plus 17 changes to basic strategy, each triggered when the Hi-Lo true count reaches a set number. This is the full list, with the count that triggers each play.

The Illustrious 18 at a glance
Count	Hi-Lo true count (Hi-Lo guide)
Plays	18: insurance and 17 hand plays
Triggered	13 at or above the index, 5 below it
Game	Multi-deck, dealer stands on soft 17, no surrender

The 18 plays

When the true count meets the index, make the deviation. Otherwise play basic strategy.

The Illustrious 18 index plays: hand, deviation, Hi-Lo true count and the basic strategy play it replaces
Hand vs dealer	Deviation	True count	Basic strategy
Insurance vs A	Take insurance	+3 or higher	No insurance
16 vs 10	Stand	0 or higher	Hit
15 vs 10	Stand	+4 or higher	Hit
10,10 vs 5	Split	+5 or higher	Stand
10,10 vs 6	Split	+4 or higher	Stand
10 vs 10	Double	+4 or higher	Hit
12 vs 3	Stand	+2 or higher	Hit
12 vs 2	Stand	+3 or higher	Hit
11 vs A	Double	+1 or higher	Hit
9 vs 2	Double	+1 or higher	Hit
10 vs A	Double	+4 or higher	Hit
9 vs 7	Double	+3 or higher	Hit
16 vs 9	Stand	+5 or higher	Hit
13 vs 2	Hit	below −1	Stand
12 vs 4	Hit	below 0	Stand
12 vs 5	Hit	below −2	Stand
12 vs 6	Hit	below −1	Stand
13 vs 3	Hit	below −2	Stand

Counting Edge lists these in the same order under Strategy Deviations on its cheat sheet and highlights the plays that apply at the live true count. The shorter Hi-Lo list on the basic strategy chart leaves out the five plays that run below an index.

How to apply an index

At or above: for the first 13 plays, make the deviation when the true count equals the index or is higher. Stand on 16 against a 10 at 0 or more; split tens against a 6 at +4 or more.
Below: the last five plays run the other way. Basic strategy stands on 12 against a 4, and you hit only when the true count drops below 0.
Don't round up, and don't truncate toward zero. A true count of +3.9 has not reached +4. A true count of −0.9 is still below 0, though truncating it gives 0 and tells you to stand on 16 against a 10 while the shoe still favours the dealer.

Counting Edge decides on the true count it shows, to one decimal place. For whole-number indexes that is the same as rounding the displayed count down. Not sure how to get the true count? Use the true count calculator.

Insurance

Insurance pays 2 to 1, so it is worth taking when more than one unseen card in three is a ten. A high Hi-Lo true count means the shoe is rich in tens, and +3 is the index at which Counting Edge tells you to take it. Below +3, decline.

The Fab 4: late surrender indexes

If the table offers late surrender, four more plays depend on the count. Surrender at or above the index, and play the hand without surrendering below it.

The Fab 4 late surrender indexes
Hand vs dealer	Surrender at true count
14 vs 10	+3 or higher
15 vs 10	0 or higher
15 vs 9	+2 or higher
15 vs A	+1 or higher (S17), −1 or higher (H17)

When surrender is on, it replaces the stand plays on the same hands: Counting Edge shows surrender for 16 against a 9 or 10 at every count, and for 15 against a 10 from a true count of 0. The basic strategy chart lists the plain surrender plays.

One more play in the app

Counting Edge adds a play that is not one of the 18: stand on 15 against an ace at a true count of +5 or higher (when surrender is off).

Using the indexes with other counts

The numbers above are Hi-Lo true counts. A Level 2 or Level 3 count runs on a different scale, so the same shoe gives a bigger true count: Hi-Opt II about 1.67 times Hi-Lo's, Omega II and Zen Count about 1.79 times, Wong Halves about 1.05 times. Counting Edge multiplies each index by that factor and rounds to one decimal place:

The Illustrious 18 indexes converted for Hi-Opt II, Omega II and Zen Count, and Wong Halves
Hand vs dealer	Deviation	Hi-Lo	Hi-Opt II	Omega II, Zen	Wong Halves
Insurance vs A	Take insurance	+3 or higher	+5 or higher	+5.4 or higher	+3.1 or higher
16 vs 10	Stand	0 or higher	0 or higher	0 or higher	0 or higher
15 vs 10	Stand	+4 or higher	+6.7 or higher	+7.2 or higher	+4.2 or higher
10,10 vs 5	Split	+5 or higher	+8.4 or higher	+8.9 or higher	+5.2 or higher
10,10 vs 6	Split	+4 or higher	+6.7 or higher	+7.2 or higher	+4.2 or higher
10 vs 10	Double	+4 or higher	+6.7 or higher	+7.2 or higher	+4.2 or higher
12 vs 3	Stand	+2 or higher	+3.3 or higher	+3.6 or higher	+2.1 or higher
12 vs 2	Stand	+3 or higher	+5 or higher	+5.4 or higher	+3.1 or higher
11 vs A	Double	+1 or higher	+1.7 or higher	+1.8 or higher	+1 or higher
9 vs 2	Double	+1 or higher	+1.7 or higher	+1.8 or higher	+1 or higher
10 vs A	Double	+4 or higher	+6.7 or higher	+7.2 or higher	+4.2 or higher
9 vs 7	Double	+3 or higher	+5 or higher	+5.4 or higher	+3.1 or higher
16 vs 9	Stand	+5 or higher	+8.4 or higher	+8.9 or higher	+5.2 or higher
13 vs 2	Hit	below −1	below −1.7	below −1.8	below −1
12 vs 4	Hit	below 0	below 0	below 0	below 0
12 vs 5	Hit	below −2	below −3.3	below −3.6	below −2.1
12 vs 6	Hit	below −1	below −1.7	below −1.8	below −1
13 vs 3	Hit	below −2	below −3.3	below −3.6	below −2.1

This is a scaled approximation. Books for those systems publish their own index tables, and a few of their numbers differ from these. See Hi-Opt II, Wong Halves and the other counts on the systems overview. KO and ReKO have no true count, so Counting Edge shows a key count and a pivot for them instead of index plays.

Rules change the indexes

These are multi-deck, dealer-stands-on-17 numbers. Under H17, basic strategy already doubles 11 against an ace, so that play applies at every count and the +1 index no longer matters. Published tables for H17 and for one or two decks differ in a few other indexes, so use one built for your game if you play those.

How to learn them

Basic strategy and your bet ramp come first: they are worth more than any index. Then add the deviations a few at a time, starting with insurance, 16 against 10 and 15 against 10, which come up most. Drill the count in the card counting practice trainer, and check your basic strategy in the basic strategy trainer. The app marks each deviation cell on its chart as the count moves.

Sources

CounterStrategyEngine.kt in the Counting Edge source: the index plays, their true counts and the Fab 4 surrender plays
TrueCountScaling.kt in the Counting Edge source: how indexes are converted for other counting systems
CounterCalculations.kt in the Counting Edge source: the true count to one decimal place
Don Schlesinger, Blackjack Attack: the Illustrious 18 and the Fab 4
How this site's figures are checked: About

Frequently asked questions

What are the Illustrious 18?

A list of 18 Hi-Lo index plays from Don Schlesinger's Blackjack Attack: insurance plus 17 changes to basic strategy, each triggered when the true count reaches a set number.

Do I need to learn all 18 at once?

No. Get basic strategy and your bet ramp right first, then add the indexes a few at a time. Insurance, 16 against 10 and 15 against 10 come up often, so start with those.

Should I round the true count before checking an index?

Make the play only once the true count has reached the index. Counting Edge compares the true count to one decimal place, so +3.9 has not reached +4 and −0.9 is still below 0. For whole-number indexes that is the same as rounding the displayed count down.

Do the Illustrious 18 change if the dealer hits soft 17?

These are Hi-Lo indexes for multi-deck games where the dealer stands on soft 17. Counting Edge uses the same numbers under H17, except that basic strategy already doubles 11 against an ace there, so that play applies at every count. Published tables for H17 and for one or two decks differ in a few indexes.

Practice on Android

See Each Deviation Light Up at Its Count

Counting Edge tracks the count as you tap cards and highlights each deviation on its cheat sheet and strategy chart the moment the true count reaches the index. Free and open source.

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