Unless they support it, there’s no other “great” way to reliably trigger a Zap via an Asana Rule, without causing a more “significant” action to a task (such as a task completion).
Tagging seems like a very basic and simple method that could have been used in an Asana rule to trigger a Zap. Ideally a POST webhook feature would be implemented as an Asana rule action, but until something is reliably implemented there (been using iDO’s for a while, but unfortunately isn’t reliable enough — possibly due to Cloudfront API errors after infrastructure change), I was hoping to just make use of tagging (since Zapier has the ability to trigger when a specific tag is added).
So, once again, we’ll have to rely on 3rd party app integration for a relatively basic “Rule” action of for “Do this” of “add tag to task”.