The Illustrious 18: Count-Based Strategy Deviations That Matter

Don Schlesinger's canonical set of 18 highest-value deviations from . The full table, the math, and how to actually use it at the table.

What It Is

The Illustrious 18 is a ranked list of the 18 most valuable count-based deviations from basic strategy for a counter, published by Don Schlesinger in Blackjack Attack. Each entry says: at a specific threshold, deviate from the chart and play a different action.

Schlesinger ranked them by total EV gain — the product of how often the situation arises and how much EV the deviation adds each time. Number 1 on the list (insurance at +3) is worth more than the bottom four combined. Pros who learn the Illustrious 18 capture roughly 90–95% of the full-indices deviation EV available — the diminishing returns after 18 are real.

The Full Set

Thresholds assume Hi-Lo with true-count conversion (running count divided by decks remaining). "≥" means play the deviation when the true count meets or exceeds that value; "<" means play it at or below.

#	Situation	True-Count Trigger	Deviation	Baseline
1	Insurance	≥ +3	Take insurance	Never insure
2	Hard 16 vs 10	≥ 0	Stand	Hit
3	Hard 15 vs 10	≥ +4	Stand	Hit
4	Pair of 10s vs 5	≥ +5	Split	Stand
5	Pair of 10s vs 6	≥ +4	Split	Stand
6	Hard 10 vs 10	≥ +4	Double	Hit
7	Hard 12 vs 3	≥ +2	Stand	Hit
8	Hard 12 vs 2	≥ +3	Stand	Hit
9	Hard 11 vs A	≥ +1	Double	Hit
10	Hard 9 vs 2	≥ +1	Double	Hit
11	Hard 10 vs A	≥ +4	Double	Hit
12	Hard 9 vs 7	≥ +3	Double	Hit
13	Hard 16 vs 9	≥ +5	Stand	Hit
14	Hard 13 vs 2	< −1	Hit	Stand
15	Hard 12 vs 4	< 0	Hit	Stand
16	Hard 12 vs 5	< −2	Hit	Stand
17	Hard 12 vs 6	< −1	Hit	Stand
18	Hard 13 vs 3	< −2	Hit	Stand

Why These 18

The cutoff is empirical, not arbitrary. Schlesinger ran simulations of every plausible deviation across thousands of shoes and ranked them by the EV gain a perfect player captures by knowing that index. The 18 chosen cover roughly 90% of the total deviation value; adding indices 19 through ~150 picks up the last 10% and massively increases the memorization load.

Most pros learn the full 18, then add the if they play games with late surrender. Beyond that, only full-time counters with deep games and minimal cover concerns bother with additional indices.

How To Use Them

Each deviation is a simple rule of the form: "if TC {≥|<} X, play {action}; otherwise play basic strategy." At the table, a counter runs the count continuously, converts to true count on each bet cycle, and mentally flags any upcoming deviation situation.

Example: hard 16 vs dealer 10. Basic strategy says hit. But the Illustrious 18 says stand when TC ≥ 0. If you're at a true count of +1 and dealt a 10-6 against a dealer 10, you stand instead of hitting. That single decision is worth about 0.31% extra EV over the hand — and since the situation comes up frequently, it's the second-most-valuable deviation on the list.

Caveats Worth Knowing

Indices are Hi-Lo-specific. The thresholds above assume Hi-Lo tags (+1 for 2–6, 0 for 7–9, −1 for 10–A). KO and other unbalanced counts use different thresholds. Hi-Opt II, Zen, and other stronger systems have their own indices with typically lower thresholds (they're more playing-efficient).

The 10-10 split deviations are cover-sensitive. Splitting tens at a high count is a classic counter tell — dealers and pit bosses notice. Many pros skip indices 4 and 5 as cover compromise and absorb the small EV cost.

Penetration matters. Deviations are most valuable in the back half of the shoe where true counts can swing. In a game with 50% penetration (half the shoe cut off), you'll see the high-value deviations less often and the total EV gain shrinks proportionally.

Test the Illustrious 18 in the simulator.
Run a million hands with and without deviation indices and see the EV difference for your specific rule set.

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