Sword of the Necromancer has exclusive IR Codes that can be redeemed for exclusive content such as bonuses, buffs, and weapons. The designer of the
Game continually makes new codes available so be sure to check out their Twitter
IR Code checklist to acquire new ones.
To redeem your IR Codes you simply have to scan it, take a look at the video below to see how you scan an IR code with the Nintendo Switch Right Joycon's IR Camera.
To manually input the IR Code on other consoles press the 'Read Code' option. You then need to select the square in the 8x8 grid and change it's value with the 'Accept' button. Once the grid matches the IR Code from your card, press the 'Validate Code' to validate the code and get the item. The IR codes you input into your game are not permanent, you need to enter a new code every time you want to take one of the items, as they are single-use.