You can't change attributes with macros. The short rule is, nothing that is on the character sheet can be changed or altered with macros - macros can only output to chat and initiative. Best you can do is to link AC to one of the token bars, and change that as needed. EDIT: A really janky way to get a on-token toggle for an AC modifier is to 1. enable global ac modifiers section in the sheet settings 2. create an attribute called "aaa" 3. link a token bar to the "aaa" attribute 4. rename the "aaa" attribute to "repeating_acmod_$0_global_ac_active_flag" (no quotes) 5. input a value between 0 and 1 in the attribute 6. now go back to the sheet and you should find an empty global ac modifier entry. Fill it in as you like. Now you have an ac field that is controlled by changing the token bar value between 0 and 1. EDIT2: On further testing, the ac modifier produced this way appears to be quite bugged. Don't follow the steps above if you don't want to break your character sheet. EDIT3: A method that shouldn't break your sheet though, is to have a token bar linked to global_ac_mod_flag - changing the value of that attribute from 1 to 0 hides all your AC modifiers and deactivates them, and changing it from 0 to 1 reveals them, and activates each that is checked on.