Slayer Study vs Crimson Templar Fiendish Study

[Myronnis]

I have a Slayer level 6(deliverer) with Crimson Templar Level 4 who also gains Fiendish Studies, Both stack according to the rules but they are both Immediate Action when you Sneak attack a foe, but Immediate are also considered 1 per turn as Swift are

First question is Do I need to trigger them both seperatly or they both happen on 1 Sneak Attack (If I sneak an Outsider Evil)

And Does Lenses of Predatory Gaze increase Both or just the Slayer Study level? since both, are they both the same as slayer study

[Mysterious Stranger]

RAW they are separate abilities so need to be activated individually. Since you can only perform a single immediate action in a phase only one will be triggered on a sneak attack.

That being said, the abilities are very similar so I can see a GM allowing them to be used at the same time. Check with your GM and see if he will allow it as a house rule.

As to the lenses it only applies to the slayer levels. The Fiendish Studies is actually better than Studied Target, so is not the same thing.