What Are the Illustrious 18?
The Illustrious 18 are the eighteen basic strategy deviations that produce the most expected value gain for Hi-Lo card counters. They were identified by Don Schlesinger in his book Blackjack Attack through analysis of which deviations contribute the most to a counter’s hourly win rate.
There are hundreds of possible count-based deviations, but most contribute tiny fractions of a percent to your edge. The Illustrious 18 capture the vast majority of the total deviation value. Learning these 18 plays gives you roughly 80% of the benefit of knowing every possible deviation, with a fraction of the memorization effort.
Complete Illustrious 18 (Hi-Lo, 6-Deck S17)
Index numbers indicate the true count at which you deviate from basic strategy. "TC 0+" means deviate when the true count is zero or higher.
| # | Hand | Basic Play | Deviation | Index (TC) |
|---|
| 1 | Insurance | No | Yes (take insurance) | +3 |
| 2 | 16 vs 10 | Hit | Stand | 0 |
| 3 | 15 vs 10 | Hit | Stand | +4 |
| 4 | 10,10 vs 5 | Stand | Split | +5 |
| 5 | 10,10 vs 6 | Stand | Split | +4 |
| 6 | 10 vs 10 | Hit | Double | +4 |
| 7 | 12 vs 3 | Hit | Stand | +2 |
| 8 | 12 vs 2 | Hit | Stand | +3 |
| 9 | 11 vs A | Hit | Double | +1 |
| 10 | 9 vs 2 | Hit | Double | +1 |
| 11 | 10 vs A | Hit | Double | +4 |
| 12 | 9 vs 7 | Hit | Double | +3 |
| 13 | 16 vs 9 | Hit | Stand | +5 |
| 14 | 13 vs 2 | Stand | Hit | −1 |
| 15 | 12 vs 4 | Stand | Hit | 0 |
| 16 | 12 vs 5 | Stand | Hit | −2 |
| 17 | 12 vs 6 | Stand | Hit | −1 |
| 18 | 13 vs 3 | Stand | Hit | −2 |
Index values shown are for 6-deck S17 with DAS. Values shift by 1-2 points for H17 or different deck counts. Always calibrate to your specific game.
Why These 18 Matter Most
The deviations are ranked roughly by their contribution to hourly expected value. The top plays contribute the most because they either occur frequently or involve large EV swings:
- Insurance (TC +3): Occurs every time the dealer shows an ace. At high counts, the EV swing is substantial. See the insurance math guide.
- 16 vs 10 (TC 0): This hand occurs constantly. Standing instead of hitting at TC 0+ saves significant money over thousands of hands because the remaining ten-rich deck makes hitting more dangerous.
- 10,10 splits (TC +4/+5): Splitting tens goes against every instinct, but at high counts the extra ten density makes each split hand very strong. The EV gain is large when conditions are right.
- Negative-index deviations (13 vs 2 at TC −1, 12 vs 5 at TC −2): These tell you to hit stiff hands at low counts when the deck is poor. Basic strategy says stand, but with fewer tens remaining, the risk of busting drops and the dealer’s chance of making a hand increases, making hitting the better play.
How to Memorize Them
Do not try to learn all 18 at once. Follow this progressive approach:
- Start with the top 6. Insurance, 16 vs 10, 15 vs 10, 10 vs 10 double, 12 vs 3, and 12 vs 2. These capture the most value and are the easiest to remember.
- Add 2 new deviations per week. Only after your current set is at 95%+ accuracy under time pressure in the Blackjack 3000 deviation trainer.
- Group by pattern. Deviations 14-18 all involve hitting stiff hands at negative counts. They share the same logic: fewer tens in the deck makes it safer to hit and less likely the dealer will bust.
- Use the spaced repetition heatmap. The trainer tracks which deviations you miss and quizzes them more frequently. Trust the system — it will surface your weak spots.
The Fab 4 Surrender Deviations
If your game offers late surrender, add these four plays to your deviation repertoire. They are separate from the Illustrious 18 but also high-value:
| Hand | Dealer | Surrender at TC |
|---|
| 14 vs 10 | 10 | +3 |
| 15 vs 10 | 10 | 0 (always surrender) |
| 15 vs 9 | 9 | +2 |
| 15 vs A | A | +1 |
Surrender is one of the most underused plays in blackjack. Players hate giving up half their bet, but folding a losing hand at the right time saves more money than playing it out.
Frequently Asked Questions
Do I need to learn all 18 to be a successful counter?
No. The top 6 deviations capture over half of the total deviation value. Many successful counters play with only 10-12 of the 18 memorized. It is better to know 6 deviations perfectly than 18 imperfectly.
Do the index numbers change for different count systems?
Yes. The indices listed here are for Hi-Lo. Other systems (KO, Hi-Opt I, Hi-Opt II, Zen) have different index values for the same deviations because their tag values differ. Always use indices matched to your counting system.
Should I really split 10s?
At TC +4 or +5, yes. It feels terrible and draws attention, so many counters skip this deviation in live play (it is a major tell). The EV gain is real, but the camouflage cost may outweigh it depending on your heat tolerance.
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