How do I get Rules to see my custom entity?
Individual rules can have a type associated with them. Most rules work with Nodes but an Entity is 1 object up in the type hierarchy of Drupal. therefore rule(s) defined with the Rules module must be made aware that they are compatible with your custom entity type.

You would do this with an alter hook for Rules, or providing property information for your Entity:
I can&#39;t set a data value using rule on a custom entity