[Boss Rush] Implement for TH05

Theoretically, the same method should work for TH04 as well, but for
some reason, the Stage 3 boss gets stuck on the first phase if we do
this?

th05/formats/std.asm

@@ -56,14 +56,15 @@ std_load	proc near
 	repne scasb
 	lea	ax, [di+5]
 	mov	_tile_index_ptr, ax
-	mov	_tile_row, 0
+	xor	al, al
+	mov	_tile_row, al
+	mov	_tile_scrollspeed, al	; 0 immediately triggers the boss battle
 	movzx	ax, byte ptr es:[di]
 	inc	ax
 	add	di, ax
 	lea	ax, [di+5]
 	mov	_tile_scrollspeed_ptr, ax
 	movzx	ax, byte ptr es:[di]
-	mov	_tile_scrollspeed, al
 	inc	ax
 	add	di, ax
 	mov	dl, es:[di]
@@ -81,7 +82,7 @@ std_load	proc near
 	inc	di
 	mov	word ptr _std_ip+2, es
 	mov	word ptr _std_ip, di
-	setfarfp	_stage_vm, std_run
+	setfarfp	_stage_vm, nullsub_1
 	pop	di
 	pop	si
 	retn

th05_main.asm

@@ -583,7 +583,7 @@ loc_B099:
 loc_B09F:
 		cmp	si, 8
 		jl	short loc_B099
-		mov	power, 1
+		mov	power, 128	; Start with full power
 		mov	dream, 1
 		call	sub_E528
 		mov	al, playchar
@@ -24062,6 +24062,7 @@ sub_172FF	endp
 ; Attributes: bp-based frame
 
 sub_17322	proc far
+		retf	; Disable midbosses
 		push	bp
 		mov	bp, sp
 		mov	ax, frames_until_midboss
@@ -24078,7 +24079,6 @@ sub_17322	proc far
 
 loc_17352:
 		pop	bp
-		retf
 sub_17322	endp