Some investigation on packets, mostly the same as rof2 / laurion but not entirely.

obr/packets/login/OP_ExpansionList.txt

@@ -1 +1,22 @@
-// 0x30
+// 0x31
+
+struct Expansion
+{
+    u32 index;
+    u8 owned;
+    s32 expansion_name_string_id;
+    s32 order_string_id;
+    s32 unknown_string_id;
+    u32 unknown17;
+    
+};
+
+struct Packet {
+    u32 unknown00;
+    u32 unknown04;
+    u16 unknown08;
+    u32 expansion_count;
+    Expansion expansions[expansion_count];
+};
+
+Packet packet @0x00;