diff --git a/src/client/frontend/flow-state.ts b/src/client/frontend/flow-state.ts
index 02a7158..2ad8ea2 100644
--- a/src/client/frontend/flow-state.ts
+++ b/src/client/frontend/flow-state.ts
@@ -118,7 +118,7 @@ export interface RosterCharacter {
   isExpansion: boolean
   readonly isHardcore: boolean
   readonly isLadder: boolean
-  /** 5-bit character progression (`0..15`) from MCP 33-byte `statString[27] & 0x1f` (`D2Launch.dll` 0x6fa4c887). */
+  /** 5-bit character progression (`0..15`) from MCP 33-byte `(statString[27] >>> 1) & 0x1f` (`Fog.#10085` / `D2Launch.dll` 0x6fa4c887). */
   progression?: number | undefined
   /** Optional explicit highest unlocked difficulty override. */
   maxDifficulty?: GameDifficulty | undefined
@@ -1997,7 +1997,7 @@ export function charSummaryToRosterCharacter(
     statBytes.length > 27 &&
     statBytes[27] !== 0xff
   ) {
-    progression = statBytes[27]! & 0x1f
+    progression = (statBytes[27]! >>> 1) & 0x1f
   }
   if (
     progression === undefined ||
diff --git a/src/client/frontend/statstring-avatar.ts b/src/client/frontend/statstring-avatar.ts
index bac4531..10c9c08 100644
--- a/src/client/frontend/statstring-avatar.ts
+++ b/src/client/frontend/statstring-avatar.ts
@@ -10,7 +10,7 @@
  * - `[14..24]`: 11 component dye color indices (`0xFF` = uncolored, `0..20` = `Colors.txt` transform index)
  * - `[25]`: character level (`1..99`)
  * - `[26]`: status flags (`0x04` Hardcore, `0x08` Dead, `0x20` Expansion, `0x40` Ladder)
- * - `[27]`: `actAndDiff` (`bits 0..4` = 5-bit progression)
+ * - `[27]`: `actAndDiff` (`(nPackedValue >>> 7) | 0x80`, `bits 1..5` = 5-bit progression)
  */
 
 import type { CampfireClassId } from './flow-state.ts'
diff --git a/src/client/map/level-view.ts b/src/client/map/level-view.ts
index e1ef595..a07d0ca 100644
--- a/src/client/map/level-view.ts
+++ b/src/client/map/level-view.ts
@@ -49,6 +49,7 @@ import type { PackedTilePlacement, TileAtlas } from './tile-atlas.ts'
 export interface LevelDrawItem extends IsoDraw {
   readonly dt1Path: string
   readonly placement: PackedTilePlacement | null
+  readonly blockCount?: number | undefined
   readonly animatedPlacements?: readonly (PackedTilePlacement | null)[]
 }
 
@@ -235,13 +236,15 @@ function enrichDraws(
       )
     }
     const atlasEntry = tileAtlas?.getFrameByLibraryTile(dt1Path, draw.tile)
-    if (tileAtlas && (!atlasEntry || !atlasEntry.placement)) {
+    const libTile = libraries[draw.library]?.tiles[draw.tile]
+    const blockCount = atlasEntry?.blockCount ?? libTile?.blocks.length
+    if (tileAtlas && (!atlasEntry || (!atlasEntry.placement && blockCount !== 0))) {
       reportMissingArt('tile', dt1Path, `Missing tile placement for tileIndex=${String(draw.tile)}`)
     }
     const placement = atlasEntry?.placement ?? null
     let animatedPlacements: (PackedTilePlacement | null)[] | undefined
     if (draw.animatedFrames && draw.animatedFrames.length > 1 && tileAtlas) {
-      const tile = libraries[draw.library]?.tiles[draw.tile]
+      const tile = libTile
       if (tile && isAnimatedTile(tile)) {
         const candidates = tileAtlas
           .getFramesByStyleSeqType(dt1Path, tile.style, tile.sequence, tile.type)
@@ -250,7 +253,7 @@ function enrichDraws(
           .sort((a, b) => a.rarityFrameIndex - b.rarityFrameIndex || a.index - b.index)
         if (candidates.length > 1) {
           for (const c of candidates) {
-            if (!c.placement) {
+            if (!c.placement && c.blockCount > 0) {
               reportMissingArt(
                 'tile',
                 dt1Path,
@@ -266,6 +269,7 @@ function enrichDraws(
       ...draw,
       dt1Path,
       placement,
+      ...(blockCount !== undefined ? { blockCount } : {}),
       ...(animatedPlacements !== undefined ? { animatedPlacements } : {}),
     }
   })
diff --git a/src/client/scene/world-renderer.ts b/src/client/scene/world-renderer.ts
index f6d4686..0e12d70 100644
--- a/src/client/scene/world-renderer.ts
+++ b/src/client/scene/world-renderer.ts
@@ -1098,7 +1098,7 @@ export function renderSceneSourceFrame(ctx: SceneSourceRenderContext): SceneFram
         const w = sortedWalls[wallIdx]!
         if (w.sortY > maxSortY) break
         const h = w.placement?.height ?? 40
-        if (!w.placement) {
+        if (!w.placement && w.blockCount !== 0) {
           reportMissingArt(
             'tile',
             `wall:${w.cellX},${w.cellY}`,
diff --git a/src/client/view/scene-source.ts b/src/client/view/scene-source.ts
index 648a604..575eaed 100644
--- a/src/client/view/scene-source.ts
+++ b/src/client/view/scene-source.ts
@@ -41,6 +41,7 @@ export interface SceneTileQuad {
   readonly tile: number
   readonly dt1Path: string
   readonly placement: PackedTilePlacement | null
+  readonly blockCount?: number | undefined
   readonly animatedPlacements?: readonly (PackedTilePlacement | null)[] | null | undefined
 }
 
@@ -145,6 +146,7 @@ function mapLevelDrawToQuad(item: LevelDrawItem, fallbackActId: number): SceneTi
     tile: item.tile,
     dt1Path: item.dt1Path,
     placement: item.placement,
+    ...(item.blockCount !== undefined ? { blockCount: item.blockCount } : {}),
     animatedPlacements: item.animatedPlacements,
   }
 }
@@ -330,16 +332,19 @@ export class ClientWorldSceneSource implements SceneSource {
       const maxY = cameraTopLeft.y + profile.height + cullPaddingPx
 
       for (const f of st.levelView.floors) {
+        if (!f.placement && f.blockCount === 0) continue
         if (f.x >= minX && f.x <= maxX && f.y >= minY && f.y <= maxY) {
           floorQuads.push(mapLevelDrawToQuad(f, actId))
         }
       }
       for (const s of st.levelView.shadows) {
+        if (!s.placement && s.blockCount === 0) continue
         if (s.x >= minX && s.x <= maxX && s.y >= minY && s.y <= maxY) {
           shadowQuads.push(mapLevelDrawToQuad(s, actId))
         }
       }
       for (const w of st.levelView.walls) {
+        if (!w.placement && w.blockCount === 0) continue
         if (w.x >= minX && w.x <= maxX && w.y >= minY && w.y <= maxY) {
           const quad = mapLevelDrawToQuad(w, actId)
           if (w.roofHeight !== undefined && w.roofHeight > 0) {
diff --git a/src/netproto/mcp/packets.ts b/src/netproto/mcp/packets.ts
index b2a1d9d..9fb89ab 100644
--- a/src/netproto/mcp/packets.ts
+++ b/src/netproto/mcp/packets.ts
@@ -81,7 +81,8 @@ export type DecodedMcpS2cPacket =
  * - `[11]`: `charClass + 1` (`1..7` -> `0..6`)
  * - `[12]`: `charLevel` (`1..99`)
  * - `[13]`: `charFlags` (`0x04` Hardcore, `0x08` Dead, `0x20` Expansion, `0x40` Ladder)
- * - `[26]`: `actAndDiff`
+ * - `[26]`: `charFlags` low 7 bits | `0x80` (`0x04` Hardcore, `0x08` Dead, `0x20` Expansion, `0x40` Ladder)
+ * - `[27]`: `actAndDiff` (`(nPackedValue >>> 7) | 0x80`, where `bits 1..5` = 5-bit `nProgression`)
  */
 export function parseMcpCharStatString(
   name: string,
@@ -103,12 +104,18 @@ export function parseMcpCharStatString(
   const flags = isFull33 ? statBytes[26]! : statBytes.length > 13 ? statBytes[13]! : McpCharFlag.EXPANSION
   const expansion = (flags & McpCharFlag.EXPANSION) !== 0
   const actAndDiff = isFull33 && statBytes.length > 27 ? statBytes[27]! : statBytes.length > 26 ? statBytes[26]! : 0
-  // Per D2Launch.dll (0x6fa4c887..0x6fa4c910) & D2Multi.dll (0x6f9e5182..0x6f9e52cd):
-  // statBytes[27] & 0x1f is the 5-bit character progression (0..15, acts completed across Normal/Nightmare/Hell).
+  // Per D2Game.dll CLIENTS_FillCharacterPreviewInfo (0x6FC32810), Fog.#10085 FOG_Encode14BitsToString,
+  // and D2Launch.dll (0x6fa4c887..0x6fa4c910):
+  // D2PackedClientSaveFlags packs 5-bit nProgression at bits 8..12 (CLIENTSAVEFLAG_CHARACTER_PROGRESSION_BIT = 8).
+  // FOG_Encode14BitsToString splits the 14-bit value into two 7-bit bytes with 0x80 set:
+  //   statBytes[26] = (nPackedValue & 0x7f) | 0x80
+  //   statBytes[27] = ((nPackedValue >>> 7) & 0x7f) | 0x80
+  // Therefore bits 1..5 of statBytes[27] hold the 5-bit character progression: (statBytes[27] >>> 1) & 0x1f.
   // Expansion (5 acts/difficulty): >= 10 -> Hell (2), >= 5 -> Nightmare (1), else Normal (0).
   // Classic (4 acts/difficulty):   >= 8  -> Hell (2), >= 4 -> Nightmare (1), else Normal (0).
-  const progression = actAndDiff & 0x1f
-  const act = ((actAndDiff & 0x07) % 5) + 1
+  const progression = (actAndDiff >>> 1) & 0x1f
+  const actsPerDiff = expansion ? 5 : 4
+  const act = (progression % actsPerDiff) + 1
   const difficulty: 0 | 1 | 2 = expansion
     ? progression >= 10
       ? 2
diff --git a/tests/client/drlg-map-motion.test.ts b/tests/client/drlg-map-motion.test.ts
index cec915f..15d4e35 100644
--- a/tests/client/drlg-map-motion.test.ts
+++ b/tests/client/drlg-map-motion.test.ts
@@ -44,6 +44,10 @@ import {
   D2_BASE_WALK_SUBTILES_PER_SEC,
   LocalMovementPredictor,
 } from '../../src/client/motion/predictor.ts'
+import {
+  clearMissingArtEntries,
+  getMissingArtEntries,
+} from '../../src/client/scene/world-renderer.ts'
 import { COLLIDE_MASK_INVALID } from '../../src/common/world/d2map.ts'
 
 const TILES_PACK_DIR = path.resolve('public/act-packs/tiles')
@@ -220,6 +224,7 @@ describe('Milestone M3 — TileAtlas, Runtime DRLG (136 Levels), Client Motion &
 
       const seed = 0x12345678
       let verifiedLevels = 0
+      clearMissingArtEntries()
 
       for (const range of actLevelRanges) {
         mapService.loadAct({ act: range.act, seed, difficulty: 0 })
@@ -264,6 +269,17 @@ describe('Milestone M3 — TileAtlas, Runtime DRLG (136 Levels), Client Motion &
       }
 
       expect(verifiedLevels).toBe(136)
+      // Zero-block collision/marker DT1 tiles (e.g. baallair\floor.dt1 tileIndex=109 in Area 129)
+      // must not trigger spurious [D2MissingArt] reports (#739).
+      expect(getMissingArtEntries()).toEqual([])
+
+      const baalFloor109 = tileAtlas.getFrameByLibraryTile(
+        'data\\global\\tiles\\expansion\\baallair\\floor.dt1',
+        109,
+      )
+      expect(baalFloor109).toBeDefined()
+      expect(baalFloor109?.blockCount).toBe(0)
+      expect(baalFloor109?.placement).toBeNull()
     }, 120_000)
 
     it('round-trips world sub-tile, local sub-tile, and isometric ortho coordinates accurately', () => {
diff --git a/tests/client/frontend-batch7-batch8.test.ts b/tests/client/frontend-batch7-batch8.test.ts
index 67b379c..29928ab 100644
--- a/tests/client/frontend-batch7-batch8.test.ts
+++ b/tests/client/frontend-batch7-batch8.test.ts
@@ -249,7 +249,7 @@ describe('Batch 7 & 8 Phase 3 — Frontend Renderer & Flow State Parity (#696–
     equippedBytes[15] = 9 // TR dye -> cred (Crystal Red)
     equippedBytes[25] = 85
     equippedBytes[26] = 0xe0
-    equippedBytes[27] = 0x80 | 10
+    equippedBytes[27] = 0x80 | (10 << 1)
 
     const equippedDesc = parseMcpAvatarStatstring(equippedBytes, 'pa')
     expect(equippedDesc.hasEquippedComponents).toBe(true)
diff --git a/tests/frontend/flow-state.test.ts b/tests/frontend/flow-state.test.ts
index 34113d8..e47fa32 100644
--- a/tests/frontend/flow-state.test.ts
+++ b/tests/frontend/flow-state.test.ts
@@ -185,14 +185,24 @@ describe('Diablo II v1.13c Front-End & Battle.net Flow State Machine', () => {
     expect(getCharacterMaxDifficulty({ isExpansion: false, progression: 7 })).toBe('nightmare')
     expect(getCharacterMaxDifficulty({ isExpansion: false, progression: 8 })).toBe('hell')
 
-    // Verify 33-byte MCP statString progression parsing (statBytes[27] & 0x1f)
+    // Verify 33-byte MCP statString progression parsing ((statBytes[27] >>> 1) & 0x1f per Fog.#10085)
     const stat = new Uint8Array(33).fill(0xff)
     stat[0] = 0x84
     stat[1] = 0x80
     stat[13] = 0x04 // Paladin (3 + 1)
     stat[25] = 65
     stat[26] = 0xe0 // EXPANSION | LADDER | 0x80
-    stat[27] = 0x80 | 5 // progression = 5 (Slayer, Nightmare unlocked)
+
+    stat[27] = 0x80 | (3 << 1) // 0x86: progression = 3 (Normal Act 3, must NOT unlock Nightmare)
+    const summaryNorm3 = parseMcpCharStatString('PalNorm3', 99999, stat)
+    expect(summaryNorm3.progression).toBe(3)
+    expect(summaryNorm3.difficulty).toBe(0)
+    const rosterNorm3 = charSummaryToRosterCharacter(summaryNorm3)
+    expect(isDifficultyUnlocked(rosterNorm3, 'normal')).toBe(true)
+    expect(isDifficultyUnlocked(rosterNorm3, 'nightmare')).toBe(false)
+    expect(isDifficultyUnlocked(rosterNorm3, 'hell')).toBe(false)
+
+    stat[27] = 0x80 | (5 << 1) // 0x8a: progression = 5 (Slayer, Nightmare unlocked, Hell locked)
     const summaryNm = parseMcpCharStatString('PalSlayer', 99999, stat)
     expect(summaryNm.progression).toBe(5)
     expect(summaryNm.difficulty).toBe(1)
@@ -201,12 +211,26 @@ describe('Diablo II v1.13c Front-End & Battle.net Flow State Machine', () => {
     expect(isDifficultyUnlocked(rosterNm, 'nightmare')).toBe(true)
     expect(isDifficultyUnlocked(rosterNm, 'hell')).toBe(false)
 
-    stat[27] = 0x80 | 10 // progression = 10 (Champion/Patriarch, Hell unlocked)
+    stat[27] = 0x80 | (10 << 1) // 0x94: progression = 10 (Champion, Hell unlocked)
     const summaryHell = parseMcpCharStatString('PalChamp', 99999, stat)
     expect(summaryHell.progression).toBe(10)
     expect(summaryHell.difficulty).toBe(2)
     const rosterHell = charSummaryToRosterCharacter(summaryHell)
     expect(isDifficultyUnlocked(rosterHell, 'hell')).toBe(true)
+
+    stat[27] = 0x80 | (15 << 1) // 0x9e: progression = 15 (Patriarch, all difficulties unlocked)
+    const summaryPatriarch = parseMcpCharStatString('PalPat', 99999, stat)
+    expect(summaryPatriarch.progression).toBe(15)
+    expect(summaryPatriarch.difficulty).toBe(2)
+    const rosterPatriarch = charSummaryToRosterCharacter({
+      name: 'PalPatRaw',
+      classId: 3,
+      level: 80,
+      expansion: true,
+      rawStatString: stat,
+    })
+    expect(rosterPatriarch.progression).toBe(15)
+    expect(isDifficultyUnlocked(rosterPatriarch, 'hell')).toBe(true)
   })
 
   it('validates maxPlayers (1..8) and charDifference (1..99 when enabled) in Create Game', () => {
diff --git a/tests/netproto/core-crypto-bncs-mcp.test.ts b/tests/netproto/core-crypto-bncs-mcp.test.ts
index ecc621c..3a36b43 100644
--- a/tests/netproto/core-crypto-bncs-mcp.test.ts
+++ b/tests/netproto/core-crypto-bncs-mcp.test.ts
@@ -185,13 +185,15 @@ describe('BNCS & MCP framing, packets, and sessions', () => {
     sorcStat[13] = 0x02 // Sorceress (1 + 1)
     sorcStat[25] = 42 // level 42
     sorcStat[26] = 0xe4 // 0x80 | LADDER (0x40) | EXPANSION (0x20) | HARDCORE (0x04)
-    sorcStat[27] = 0x80
+    sorcStat[27] = 0x80 | (15 << 1) // 0x9e: progression = 15 (bits 1..5 per Fog.#10085)
     const summary = parseMcpCharStatString('TestSorc', 123456, sorcStat)
     expect(summary.charClass).toBe(1)
     expect(summary.level).toBe(42)
     expect(summary.expansion).toBe(true)
     expect(summary.hardcore).toBe(true)
     expect(summary.ladder).toBe(true)
+    expect(summary.progression).toBe(15)
+    expect(summary.difficulty).toBe(2)
   })
 
   it('auto-echoes SID_PING in BncsSession and completes MCP startup over MemoryStream', async () => {