|Jim Groves Contributor, RPG Superstar 2010 Top 4|
Skeld said, "Summons as a standard action." If that's true and not a typo, that's VERY good. It is usually a full-round action to summon a monster. That's worth the Diehard or other extra benefit in and of itself. It might even be better, depending on who you ask.
You can summon this as a standard action, but they can't act until your next turn, except.... They are not flat-footed, and they can take AOOs. So you can summon your creatures in front of you and start to establish a defense perimeter and carry on normal business on your next turn.
There is also an add-on benefit if you have Sacred Summons. That way, if you have both feats you don't experience redundancy, you can get some extra benefit.
The monster list has a nice assortment of evil outsiders like divs, ausuras, kytons, daemons, and even some evil fey, as well as a few standby demons and devils (which is important because creatures not on this list aren't subject to its benefits).
Edit: Oh, I forgot, there are some gremlins on the list too. No point in summoning low level evil creatures in greater numbers? Tell that to the pugwumpis.
You're welcome, Evil.