Illustrious 18 index plays

The Illustrious 18 are the eighteen Hi-Lo playing deviations that Don Schlesinger singled out in Blackjack Attack as the ones worth learning first, together with the Fab 4, which are the four most valuable surrender deviations. Each is a true-count threshold at which the basic strategy play changes. The indices below are the Hi-Lo numbers republished with Schlesinger’s permission by Wizard of Odds, for a six-deck game with the dealer standing on soft 17, double after split, resplitting to four hands and late surrender available.

What an index is

Basic strategy is the best play against a full, unseen shoe. Once cards have been dealt the composition changes, and at some point the best play for a given hand flips. An index is the true count at which that flip happens for a specific count system and rule set.

• For a stand, double, split or insurance index, make the deviation when the true count is at or above the number.
• For a negative index, the deviation is the basic strategy play once the count drops below it. “13 v 2: −1” means stand at −1 or higher, which is the normal play, but hit at −2 or lower.

Indices are stated in true count, not running count, because the shift in composition they describe is per deck remaining; see true count conversion. They are also system-specific. Hi-Lo tags the ace as a high card, so its insurance index differs from an ace-neutral system’s, and a level-two count’s indices are on a different scale again.

The Illustrious 18 for Hi-Lo

The table follows the order in which Wizard of Odds reproduces them, which runs roughly from most to least valuable and is a sensible order to learn them in. Rows 14 to 18 are the negative indices: the basic strategy stand becomes a hit when the shoe is rich in small cards.

The Fab 4 surrender indices

These require late surrender, which many tables do not offer; see surrender. Note that 15 v 10 appears in both lists: basic strategy under these rules already surrenders 15 v 10, so the Fab 4 index of 0 means “keep surrendering unless the true count is negative”, while the Illustrious 18 index of +4 says that if surrender is not available, stand rather than hit from +4 upwards.

Why these plays are worth the most

An index is valuable in proportion to how often the hand occurs, how often the count reaches the index, and how much the right decision gains. The top entries score on all three.

Insurance (+3). Insurance is a side bet that the dealer’s hole card is a ten, paying 2:1. In a fresh six-deck shoe 96 of 312 cards are tens, and after an ace upcard the chance is 96 ÷ 311 ≈ 30.9%, short of the 33.3% needed to break even. A Hi-Lo true count of +3 indicates enough surplus tens to push the probability past a third. Because the bet is independent of your hand, the index applies whether you hold 20, a natural or a 12. Insurance and even money maths works through the figures. Schlesinger and others rank it first because the ace shows up often and the bet is up to half your stake.

16 v 10 (0). The closest decision in basic strategy, which is why the index sits at zero. Hitting and standing are nearly equal in a neutral shoe; any surplus of tens tips it to stand. It is the hand counters encounter most, and the full analysis is in expected value of hard 16 vs 10 and hard 16 vs 10.

15 v 10 (+4). Same logic one card further from the line, so it needs a stronger count.

10 v 10 (+4) and 10 v A (+4). Doubling a hard 10 against a strong upcard needs a ten-rich shoe to make the one-card draw good enough. Related: doubling down.

12 v 2 (+3) and 12 v 3 (+2). Basic strategy hits 12 against 2 and 3 because the dealer busts less often with those cards. A positive count raises both the dealer’s bust chance and your own, and standing takes over at modest counts.

10,10 v 5 (+5) and 10,10 v 6 (+4). Splitting a 20 looks reckless and draws attention, but at high counts two hands starting with a ten against a dealer 5 or 6 are worth more than one hand of 20. Schlesinger includes them for value; many counters skip them for cover.

Wizard of Odds reports that the Illustrious 18 and Fab 4 together recover about 80% to 85% of the value of using every available index in a six-deck game, with a larger shortfall in single- and double-deck games where playing decisions carry more of the counter’s edge.

How much index plays add

Using the simulation table on the same Wizard of Odds page for six decks, S17, with a 1-to-10 spread and 4.5 decks dealt, the Illustrious 18 plus Fab 4 produce a player advantage of 0.587%, against 0.608% with every index. Across the fifteen combinations he reports, the gap between I18+F4 and the full index set is never more than about 0.04 percentage points. Betting on the count does most of the work; the indices refine it.

Compare that with the effect of spread and penetration in the same table: moving from a 1-to-5 spread at four decks dealt (0.157%) to a 1-to-15 spread at five decks dealt (1.147%) changes the advantage by a full percentage point. If you have limited study time, learn the first five indices, then spend the rest on bet sizing and game selection; see bet spreads and bankroll for counters.

Using these numbers correctly

• Rule profile. The indices assume six decks and dealer stands on soft 17. The site’s own strategy chart and trainer use six decks, S17, double after split, no surrender; the Illustrious 18 apply to that game, the Fab 4 do not.
• Rounding convention. Wizard of Odds rounds the true count to the nearest whole number in his worked example. Use the same convention with these indices.
• Do not deviate on running count. A running count of +3 with four decks left is a true count under +1 and does not justify insurance.
• Cover. Wikipedia’s card counting article lists splitting tens, standing on 15 and 16 against a 10 and surrendering 14 as plays that surveillance staff associate with counters. The value of a deviation has to be weighed against being noticed.

No index turns a bad hand into a good one. Standing on 16 against a 10 at a true count of +2 still loses more often than it wins; it just loses slightly less often than hitting does.

Related reading

• Hi-Lo card counting tutorial
• True count conversion
• Insurance
• Expected value of hard 16 vs 10