Don Schlesinger's 22 highest-impact basic strategy deviations for Hi-Lo card counters. Insurance, stiffs, doubles, and surrender — the index plays that capture roughly 80% of all available deviation EV. Sourced from Blackjack Attack.
The Illustrious 18 is ranked by EV impact, not difficulty. The top 6 plays alone capture more than half of the total gain available from index play. Drill these to instinct first — under time pressure, with money on the line in mind — before adding the rest.
Then add 2 more per week, drilling each set to ~95% accuracy under time pressure before moving on.
| # | Hand | Index | Action | What's happening |
|---|
Reading the chart: For positive indices, you make the deviation play if true count is at or above the index. For negative indices (entries 14–18), you deviate to hit when true count is below the index. Insurance: take it when TC ≥ +3.
The 22 deviations cluster into a few logical patterns. Memorizing by pattern beats memorizing by row.
One play: take insurance when the true count is +3 or higher. Worth more than several other deviations combined because you get to act on it every time the dealer shows an Ace. Insurance pays 2 to 1, and breaks even when 33.3% of the deck is 10-valued. At TC +3 in Hi-Lo, you've crossed that threshold.
16 vs. 10, 15 vs. 10, 12 vs. 3, 12 vs. 2, 13 vs. 2, 16 vs. 9. Basic strategy says hit these. But when the deck is rich in 10s, the dealer is more likely to bust on their own stiff hand, AND you're more likely to bust if you hit. Standing becomes correct when the count crosses each threshold. Pattern: the harder the dealer's up card, the higher the index.
13 vs. 2, 12 vs. 4, 12 vs. 5, 12 vs. 6, 13 vs. 3. Basic strategy says stand. When the count goes negative, hit instead — the deck is poor in 10s, the dealer is less likely to bust, and you're less likely to bust if you hit. This is the "negative correlation" group: deviate when count drops below the index, not above.
10,10 vs. 5 and 6 (split), 10 vs. 10, 10 vs. A, 11 vs. A, 9 vs. 2, 9 vs. 7. Basic strategy is conservative on these. When 10s flood the deck, doubling and splitting become more profitable — you're more likely to catch a 10 to make 20, and the dealer is more likely to bust trying to beat it. Pattern: at high counts, attack with bigger bets per hand, not just bigger initial wagers.
14 vs. 10 (TC +3), 15 vs. 10 (TC 0), 15 vs. 9 (TC +2), 15 vs. A (TC +1). When the casino offers late surrender, these four plays save real money. Surrender at the right count is worth as much as Illustrious 18 entries 10–18 combined. If your casino has surrender, learning these is a high-leverage move. If they don't, ignore this group entirely.
The Illustrious 18 only matters if you're already counting cards. To use it: maintain your running count using a system like Hi-Lo, convert to true count by dividing by decks remaining, then check the chart whenever a hand matches one of the 22 deviation spots. If the true count is at or above the index (or below, for the negative-index plays), you deviate from basic strategy.
Every hand in blackjack has a "neutral deck" expected value for each action — hit, stand, double, etc. Basic strategy picks the action with the highest neutral-deck EV. But as the deck composition shifts, those EVs shift too. The Illustrious 18 are the spots where the EV ranking flips at a specific count threshold. The index number is the exact true count where one action becomes mathematically better than the basic-strategy action.
Don Schlesinger ranked all possible deviation plays by total EV gain (frequency × per-play gain) and identified the top 18 — these capture roughly 80–85% of the total deviation EV available. The Fab 4 (4 surrender plays) add another chunk on top when surrender is offered.
The exact index numbers on this page are sourced from Wizard of Odds, which republishes them with permission from Don Schlesinger's Blackjack Attack: Playing the Pros' Way, page 62 (2004 edition). They represent the standard floored Hi-Lo indices for typical six-deck rules and are the most widely-used reference in the counting community.
For exact indices broken out by deck count and S17/H17 — page 213 of Blackjack Attack 3rd edition (BJA3) is the canonical source. Differences from the values shown here are minor (usually within 1 true count point) for the standard six-deck shoe game.
Different counting systems have different index numbers for the same deviation plays, because the same true count means different things across systems. The 18 plays themselves (16 vs. 10, etc.) are the same — but a Hi-Opt II counter standing on 16 vs. 10 wouldn't use the index "0" they'd use the Hi-Opt II index for that same play, which differs.
For Hi-Opt II indices: page 213 of BJA3 covers them, or use CVCX/QFIT software to generate them for your specific system. Our card counting systems comparison covers which systems use which indices.
The Illustrious 18 + Fab 4 is the final layer of basic blackjack mastery. Beyond this lies advanced index play (the Catch-22, full Schlesinger indices) and game-specific deviation tables. For most counters, mastering basic strategy → Hi-Lo → true count → these 22 plays is enough to play with a real edge in any beatable game.
If you haven't already: review the interactive basic strategy chart, study the 9 counting systems comparison, and use the true count calculator until the conversion is instinctive. The blackjack suite on Lifes a Gambol is now complete — basic strategy + counting + true count + index plays, all interlinked, all bulletproof.
The questions counters ask most often about index plays.
The Illustrious 18 is a list of the 18 highest-impact basic strategy deviations for Hi-Lo card counters, compiled by Don Schlesinger in his book Blackjack Attack. Each deviation is tied to a specific true count threshold. When the true count crosses that number, you deviate from basic strategy and make the alternative play.
Memorizing these 18 plays captures roughly 80-85% of the gain available from index play in a six-deck game.
The Fab 4 is Don Schlesinger's list of the four most-impactful late-surrender deviations for Hi-Lo. They are separate from the Illustrious 18 because they only apply when the casino offers late surrender, but if surrender is available these four plays are highly profitable.
The Fab 4 covers surrendering 14, 15 against various dealer up cards based on true count.
Insurance is a 2-to-1 side bet that the dealer has blackjack. Mathematically, it becomes profitable when 33.3% or more of the remaining cards are 10-valued. At true count +3 or higher (in Hi-Lo), the deck has shifted enough toward 10s that this threshold is crossed.
Because insurance is offered on every hand where the dealer shows an Ace, the count gets to act on it more often than any other deviation — making it the single highest-EV index play.
The index number is the true count threshold for the deviation. For positive indices (entries 1-13 in the Illustrious 18), you make the deviation play if the true count is at or above the index. For negative indices (entries 14-18, the "stand on stiff vs weak dealer" plays), you deviate to hit when the true count is below the index.
For example: the index for 16 vs 10 is 0, meaning stand at TC ≥ 0, hit at TC < 0.
No. The Illustrious 18 index numbers are calibrated specifically for the Hi-Lo counting system. Other systems (Hi-Opt II, Omega II, Zen, Wong Halves, etc.) have different index numbers because the same true count means different things.
The plays themselves (the 18 hand vs dealer combinations) are similar across systems, but you'll need the indices generated for your specific system. CVCX or QFIT software can generate them, and Don Schlesinger's Blackjack Attack covers Hi-Opt I/II indices in detail.
No — work in order. The list is ranked by EV impact. Insurance alone is worth more than several lower-ranked plays combined. Most counting trainers recommend learning the top 6 first, drilling those to instinct under time pressure, then adding 2 more per week.
Trying to memorize all 22 at once usually leads to errors that wipe out the EV the deviations would have added.
Negative indices apply to "negative correlation" deviations — you deviate to hitting when the count drops below the threshold. The reason: a negative count means the deck is poor in 10s, which means the dealer is less likely to bust on weak up cards (2-6).
Standing on a stiff hand (12-13) against a dealer 2 or 3 only makes sense when 10s are reasonably plentiful. When the count goes very negative, hitting becomes safer because there are fewer 10s to bust you.
The Illustrious 18 indices on this page are the standard published values from Schlesinger's Blackjack Attack and represent typical Hi-Lo six-deck game conditions. Differences between S17 and H17 are minor for most of the Illustrious 18 — usually within 1 true count point.
Don Schlesinger's Blackjack Attack 3rd edition (page 213) publishes exact H17/S17 indices broken out by deck count. For practical play, the standard values work well for both rule sets.