Custom aura:
Just create new ability out of some already existing aura, modify its fields, give it custom buff, etc.
Then you trigger what the aura does (unless there's already existing some aura that does what you want in slightly different way).
Stats:
There's an ability called Attribute Bonus, which gives bonus to stats of your choice when you invest skill point in it.
If you want the ability to give last for some duration (e.g. +5 intelligence for 10 seconds), you would need to trigger it.