The Illustrious 18: the counting deviations that actually matter
Basic strategy is computed for a neutral shoe. When the count says the shoe isn't neutral, a small set of plays flip. Don Schlesinger's famous analysis ranked every possible index play by dollar value and found the top eighteen deliver the overwhelming majority of the gain — the Illustrious 18. You don't memorize hundreds of indices; you learn these.
How an index works
Each deviation is a hand, a dealer up-card, and an index number. At or above that true count, you make the deviation; below it, you play basic strategy. Example: 16 v 10 has an index of 0 — stand at any positive count, hit when the count is negative.
Why it works: a high count means tens everywhere. Your 16 busts more often when you hit (more tens for you), and the dealer's pat hands beat you more often when you stand short — but standing wins whenever the dealer draws to a bust, which also happens more with tens behind. The index is where the math crosses over.
The table
This is the subset the trainer drills (the highest-value plays for shoe games), generated from the same table the drill grader uses:
| Hand | Dealer | Index | At/above the index | Below |
|---|---|---|---|---|
| 16 | 10 | 0 | Stand | Hit |
| 15 | 10 | +4 | Stand | Hit |
| 12 | 3 | +2 | Stand | Hit |
| 12 | 2 | +3 | Stand | Hit |
| 12 | 4 | 0 | Stand | Hit |
| 13 | 2 | -1 | Stand | Hit |
| 10 | 10 | +4 | Double | Hit |
| 10 | A | +4 | Double | Hit |
| 9 | 2 | +1 | Double | Hit |
| 9 | 7 | +3 | Double | Hit |
| 10,10 | 6 | +4 | Split | Stand |
| 10,10 | 5 | +5 | Split | Stand |
(Dealer "A" = Ace. "10,10" = splitting tens — yes, really, at +4 vs a 6: the one play that makes the whole table gasp, and it's correct.)
Also in the eighteen: insurance
The single most valuable "deviation" isn't a playing change at all — take insurance at true count +3 or higher. Insurance is a side bet that the dealer's hole card is a ten; at +3 the shoe is rich enough in tens to make it profitable. Below that it's the sucker bet your grandmother warned you about.
Learn them in the right order
Value is heavily front-loaded: insurance and 16 v 10 are worth more than the rest of the table combined. The trainer teaches them in ranked order, states the true count as a premise so you drill the decision (not the counting), and only then folds deviations into full live-shoe play in the capstone. If you're still working on the count itself, start with the Hi-Lo course — deviations are the last 1%, not the first.