I might soon run an Only War one-shot with my group as a filler between campaigns / pilot for a new campaign. As such, I re-read the rules and generally got myself ready again

Looking at the Psyker, I saw Foreboding and thought "yeah, perfect! The psyker gets to evade based on his powers instead of having to specc physical stuff."

Then I looked at it more closely. Is it just me or is that power actually fairly useless?

Starting with Ag and Per fairly similar (33 and 30 respectively), for 300 xp I can either get Dodge+0 for a 33% chance at evading, or Foreboding and Per+5 for a 25% Dodge.

If I max out Foreboding by improving Per to +20, I'll have spent 1800 xp and have a 40% chance of evading an attack.
I can instead get Dodge+10 for a total of 900 xp and have a 43% chance of evading, or spend 1800 xp for an extra 10%.

And if I really want to, I can get Dodge up to 83% by maxing both the skill and Ag for 7750 xp.

I also looked at Forewarning, which it is a prereq for, and that just doesn't seem too useful either. At PR 5, casting unfettered, it is a 10% bonus, at the cost of sustaining a power.

Am I missing something here, or is Foreboding just kinda bad?

Edited to add: That's assuming I have NO matching aptitudes with Dodge - if I can somehow get my hands on the Ag aptitude, it gets even more favorable to Dodge.

Its been ages since I've read up on the OW psychic rules, but aren't you forgetting the bonuses you get to the check from your effective psy rating when manifesting the power? Its not -just- a flat Perception test.

Indeed, I missed that.

At +5 per PR, it is at least as good at the 300 xp stage as Dodge, Unfettered it is 5%, Pushed up to 15% better.

That makes it considerably better. As a Psyker wants to increase his PR anyway, for all the benefits it gets him, Foreboding is just a one-time investment. Not quite as good as dedicated Dodge, but useful still. Particularly since to be better at it, the Psyker improves in other fields as well!