Dark ones blessing macro

I cannot find any info on this specific macro entry. I am attempting to set the variable hp_temp equal to level + npcd_cha_mod the only thing I can get the macro to do is post the values of all three attributes, I cannot manage to get it to set hp_temp to a value. !{hp_temp} = @{level} + @{npcd_cha_mod} Gains Dark ones blessing

macros cannot set the value of an attribute, that requires the API.

Where can I find info on using the API?

Sorry, I should have pointed this out in my first post, was just in a hurry. The API is a Pro Subscriber Perk. &nbsp;You can access it in any game that was created by a currently active Pro subscriber. &nbsp;It's written in Javascript, and requires installing scripts in the game (which GMs and Co-GMs can both do). &nbsp;Then you can use API commands (chat strings beginning with a ! ) to activate various things. You can read about it here:&nbsp; <a href="https://wiki.roll20.net/API:Introduction" rel="nofollow">https://wiki.roll20.net/API:Introduction</a> Or chat about it here:&nbsp; <a href="https://app.roll20.net/forum/category/46806" rel="nofollow">https://app.roll20.net/forum/category/46806</a> Hope that helps!

Thanks!