A linear (merged) 3-bet range raises its best hands straight through — the strongest continuation is always "raise," no gap. A polarized range splits into two piles: genuine premiums that want a big pot, and speculative hands/blockers that 3-bet as a semi-bluff — a raise with a hand that isn't the best right now but has real ways to become it when called — with the medium hands in between just calling. Which shape fits depends mostly on stack depth and position: 3-betting out of the blinds against a wide button open tends to polarize, while 4-betting is almost always polarized — once two players have shown aggression, the calling range between them is thin.

Blockers matter most in the polarized bluffing portion of a range. A5s is the canonical example: as a 3-bet or 4-bet bluff it blocks the nut-flush/nut-broadway combos an opponent needs to continue with, while retaining backup equity (a wheel draw, a flush draw) if called. This app's own data shows it in action — in node vs3bet:BTN:vs:SB, A5s 4-bets at exactly 50% frequency (read live from node.hands.A5s), sitting alongside the range's genuine premiums purely for its blocker value — it's not there because A5s is a strong made hand.

Below is BB's actual 3-bet/call/fold split facing a UTG open — the tightest of this app's four BB-vs-RFI nodes, since UTG's own range is already the tightest range in the game. Notice the 3-bet portion is small and premium-heavy (AA,AKs,AKo:0.5,A5s:0.5,KK,QQ, read live from node.hands rather than transcribed) — exactly the polarized shape described above, appropriate against a range this strong.

Drilling below jumps to Trainer's "vs RFI" category — practice the 3-bet decision across all six shipped vs-RFI nodes; switch its Category filter to "vs 3-bet" afterward to drill the three 4-bet nodes too.