Is used to invoke a macro when a particular NFC tag is scanned. An NFC tag should be first written by MacroDroid with a specific identifier and then this identifier can be used to trigger specific instances of the NFC trigger.
Any writeable NDEF tag should be suitable for use with MacroDroid. Unfortunately it's not possible to use any other existing NFC tag (such as an access card/public transport card etc.). This is not permitted since there is no way to prevent other NFC apps also being fired, and this will require user input to select an app every time the tag is scanned.