Weapon Modifier Corruption (WMC)

A Weapon Modifier refers to the power-ups that can be found on an equipment, such as Attack Up or Durability Up. Weapon Modifier Corruption is a glitch enabled by IST to transfer data from a cooked item to a weapon, interpreting the memory as a Weapon Modifier.

During this corruption:

• The Health Recover value of the cooked item becomes the Value of the modifier.
  • For regular food, this value is the number of quarter-hearts recovered. Between 0 and 120.
  • For hearty food, this is the number of yellow hearts
• The Sell Price value of the cooked item becomes the Type of the modifier.
  • The Type is a bit-flag, so WMC can enable multiple modifiers on the same equipment.
  • See actWeapon.h for values for each modifier type

Base Mechanism

WMC is possible because:

1. The data for cooked item and the data for modifier is in the same memory location for each item. i.e. if the item is a food, then the data is used as cooked data, and if the item is a weapon, then it is used as modifier data.
   • This is only true for Visible Inventory, not GameData
2. The data for cooked item is added separately from the item itself.

In step 2, the cook data is added after adding the cook item, and the game assumes the last added item is the cook item that is supposed to receive the data.

Therefore, a WMC setup typically involves:

1. Making sure the last added item is the weapon to receive the corrupted modifier
2. Make the cooked item that donates the data failed to load while the last added item is still the weapon, transferring the data to the weapon

Note that #2 essentially means that no item should be loaded between the weapon and the cook item.

Depending on how these 2 conditions are satisfied, the WMC setups can be further categorized.

Currently, WMC is only possible when reloading the inventory from GameData (for example when reloading a save). This is because there is no known way to trigger adding a cook item during normal game play while at the same time make it so the cook item doesn’t get added succesfully.

Food Limit

Using the food limit was one of the first method to WMC. This WMC setup uses the fact that during a reload, any food after the first 60 will not load (under normal circumstances). This can be achieved by transferring 60 food into a save with a weapon, followed by the donor meal.

Example script:

get 1 hammer 1 wild-green[hp=120, price=113]
save
eat wild-green
get 60 dubious-food
!break 60 slots
reload

The step-by-step explanation:

1. Note that in the save, the items are 1 hammer and the donor meal, these are what will be added during reload
2. Note that we are transferring 60 dubious-food
3. During the reload, the hammer loads in first
4. When loading the donor meal, since there are already 60 food, it fails to load.
5. Since the last added item was the hammer, the data from the meal is transferred to the hammer

Stackable Food Limit

The reason why the previous setup required 60 broken slots, is because if we don’t transfer 60 food, then there will be food items that get loaded after the hammer. As a result, the cook data will be transferred to that item, instead of the weapon.

But wait! What if that’s exactly what we wanted? Instead of transferring the modifier directly to the weapon, we can do 2 transfers:

1. Using the Food Limit method, transfer the data from the donor meal to a Stackable food (i.e. a roasted/baked/frozen food)
2. Using Direct Inventory Corruption, corrupt the food value to >=500
3. When loading a stackable item slot, if the value being loaded plus the value of the item in the inventory is greater than 999, the stack will fail to load (this is why we need >=500 in the previous step)
4. When the stackable food fails to load, it can trigger WMC

Example script

# Setup
get 1 hammer
!break 1 slots
get 58 dubious 1 roasted-endura-carrot 1 wild-green[hp=120, price=113]

# This will make only the last food fail to load, transferring the data to the carrot
save; reload  

# Clean up the foods now
eat wild-green; eat all dubious
save

# Corrupt the carrot stack
unequip hammer
eat roasted-endura-carrot
reload
save

# Finally transfer the data to the hammer
reload

The Nullptr Exploit

Both previous setups require 60 food to make the first transfer happen. It would be really nice if that’s not the case. This is where the Nullptr Exploit comes in.

Recall that after adding the cook item (or fails to add), the game applies the cook data to the last added item without checking if it’s the cook item. However, when there is no last added item, the data is not added, and crucially, the game does not advance to the next cook data slot. This means when the next food loads, it will keep using the cook data of the previous food!

Using this exploit, 60 food is no longer required. However, this exploit is pretty tricky to trigger, this is because mLastAddedItem is only nullptr before any item is added (with one exception being the Master Sword).

Master Sword (MSWMC)

This setup triggers the Nullptr Exploit using the fact that Master Sword cannot be duplicated.

The condition for this trigger is somewhat complicated:

1. A Master Sword is transferred (can be broken or not broken)
2. The save being loaded doesn’t have Master Sword being the first item
   • This is because adding the first item skips the part check we rely on to trigger the exploit
3. The Master Sword Recharge Timer in the save being loaded is non-zero
4. The save being loaded has a Master Sword (either broken or not broken)
   • 3 and 4 usually means the save has a broken Master Sword

When all of the above conditions are met, last added item is set to nullptr, enabling the exploit.

The whole setup would be:

1. Enable the exploit as described above
2. In the same reload, load a food unsuccessfully, without loading any item in between
   • This uses the exploit described in the previous section to cause the reuse of cook data
3. Now any food that load after will have the data that’s supposed to be on the food before it
4. Continue the Stackable Food Limit setup

Travel Medallion (TMWMC)

The Travel Medallion is added in the Master Trials DLC. Unlike any other DLC items, it gets removed if you uninstall the DLC.

This can be used to trigger the Nullptr Exploit:

1. Make a save with Travel Medallion being the first item, and food after it (using Unsorted Inventory )
2. Close the game and uninstall the DLC
   • If you have physical game without DLC + digital game with DLC, this can be done by ejecting the Virtual Game Card
   • Otherwise, follow the steps on this Nintendo Support Ariticle
3. Reload the save, setup IST again to transfer some food to make the food fail to load
4. Reload the save again, the Travel Medallion will not load as the first item since DLC is uninstalled, and the next food will fail to load because of the transfer
5. Now any food that load after will have the data that’s supposed to be on the food before it
6. Continue the Stackable Food Limit setup

Unlike MSWMC, Travel Medallion does not set last added item to nullptr, so it has very limited usefulness.

Zelda Notes (ZNWMC)

Zelda Notes is an item exclusive to the Nintendo Switch 2 Edition. When you uninstall NS2E, it gets removed from your inventory and can be used to trigger the Nullptr Exploit:

1. Make a save with the Daily Bonus and Deposit Item being the first 2 items, and food after it (using Unsorted Inventory )
2. Close the game and uninstall NS2E
   • If you have the physical NS2E Game Card and the NS1E game (physical or digital), this can be done by removing the physical NS2E Game Card (then inserting the NS1E Game Card if you have a physical copy)
   • If you only have the physical NS2E Game Card, this is not possible.
   • Otherwise, follow the steps on this Nintendo Support Ariticle to download the game without NS2E
3. The rest is similar to TMWMC