In 1994, renowned blackjack mathematician Don Schlesinger published a seminal article in Blackjack Forum titled "The Illustrious 18" (later expanded in his landmark book Blackjack Attack).
While there are hundreds of theoretical index deviations in blackjack, Schlesinger proved that memorizing all of them produces diminishing returns. In fact, just 18 specific index plays capture over 80% to 85% of all potential gain from playing strategy variations.
The Complete Illustrious 18 Chart
Below is the authoritative list of the Illustrious 18 ranked in order of their financial value (EV contribution). These thresholds reflect Don Schlesinger's standard published benchmarks from Blackjack Attack, widely adopted across advantage play as the standard deviation benchmark for balanced counting systems:
| Rank | Player Hand | Dealer Upcard | Basic Strategy | Index Deviation | Standard TC Threshold |
|---|---|---|---|---|---|
| #1 | Insurance | Ace | Never Take | Take Insurance | TC ≥ +3.0 |
| #2 | 16 (Hard) | 10 | Hit | Stand | TC ≥ 0.0 |
| #3 | 15 (Hard) | 10 | Hit | Stand | TC ≥ +4.0 |
| #4 | Pair of 10s | 5 | Stand | Split | TC ≥ +5.0 |
| #5 | Pair of 10s | 6 | Stand | Split | TC ≥ +4.0 |
| #6 | 10 (Hard) | 10 | Hit | Double | TC ≥ +4.0 |
| #7 | 12 (Hard) | 3 | Hit | Stand | TC ≥ +2.0 |
| #8 | 12 (Hard) | 2 | Hit | Stand | TC ≥ +3.0 |
| #9 | 11 (Hard) | Ace | Hit (S17) / Dbl (H17) | Double Down | TC ≥ +1.0 |
| #10 | 9 (Hard) | 2 | Hit | Double Down | TC ≥ +1.0 |
| #11 | 10 (Hard) | Ace | Hit | Double Down | TC ≥ +4.0 |
| #12 | 9 (Hard) | 7 | Hit | Double Down | TC ≥ +3.0 |
| #13 | 16 (Hard) | 9 | Hit | Stand | TC ≥ +5.0 |
| #14 | 13 (Hard) | 2 | Stand | Hit | TC ≤ -1.0 |
| #15 | 12 (Hard) | 4 | Stand | Hit | TC ≤ 0.0 |
| #16 | 12 (Hard) | 5 | Stand | Hit | TC ≤ -2.0 |
| #17 | 12 (Hard) | 6 | Stand | Hit | TC ≤ -1.0 |
| #18 | 13 (Hard) | 3 | Stand | Hit | TC ≤ -2.0 |
The Most Critical Play: Insurance. Taking insurance at TC ≥ +3.0 single-handedly accounts for nearly one-third of all profits generated by playing deviations. FreeCardCounter displays a prominent gold banner the exact instant taking insurance becomes mathematically profitable.
Technical Note on Wong Halves & Deviation Indices: Don Schlesinger originally derived the Illustrious 18 for the balanced Hi-Lo system. Because Wong Halves uses fractional weights (+1.5 for 5s, -0.5 for 9s), system-specific computer simulations can yield fractional index shifts for certain boundary plays. In real-world casino play, however, advantage players and simulation engines widely use these standardized Schlesinger indices as a practical, high-efficiency benchmark for balanced counts, capturing over 95% of all potential playing deviation value.
The Fab Four Late Surrender Deviations
If the casino offers Late Surrender (LS), Don Schlesinger identified four surrender deviations (the "Fab Four") that take priority over basic hit/stand decisions:
| Player Hand | Dealer Upcard | Normal Action | Surrender Deviation | TC Threshold |
|---|---|---|---|---|
| 15 (Hard) | 10 | Hit | Late Surrender | TC ≥ 0.0 |
| 14 (Hard) | 10 | Hit | Late Surrender | TC ≥ +3.0 |
| 15 (Hard) | 9 | Hit | Late Surrender | TC ≥ +2.0 |
| 15 (Hard) | Ace | Hit | Late Surrender | TC ≥ -1.0 (H17) / +1.0 (S17) |
How FreeCardCounter Automates Deviations
Remembering 18 thresholds for Wong Halves while playing can be overwhelming. FreeCardCounter evaluates your hand, the dealer upcard, and the current fractional True Count dynamically. If an Illustrious 18 threshold is triggered, the recommendation banner pulses with an unmistakable COUNT DEVIATION alert.
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