I wonder if anybody ever tried this before. Often we need to trigger a business rule on form irrespective of the form values, something which always needs to be done. In CRM 2013, one of my colleagues pointed out to me that there is no actual need of putting any If condition. So I tried it with account name field, showing error message at all times on Account name field in Account entity. First I tried if Business rule will be allowed to be saved and activated. To my surprise, it is allowed in CRM 2013, just have a look below:
The next thing to check was what is going on in the Account form now. It had the error message as soon as I opened the form, which was permanently there(Look at highlighted rectangle in red):
So, whenever you want to trigger a business rule without any condition, it is possible to do so.
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Hope it helps!
MSDYNAMICSBLOG BY DEEPESH 
This has changed in Dynamics 365 and you now need to have a condition, which is a shame.
So you can do a workaround, in case you wish to trigger it on new entity, you can put Created on field on the form. Next say Created on does not contains data and then the action.
In case you wish to do it on save, created on contains data and then the action.
In case for all conditions you can trigger same condition in case of both ifs on Created on.
Yes, I’m not saying it’s impossible to achieve the same effect, but having to now create multiple business rules with different conditions just to make a field required on form load is a regression compared to the previous way 🙂