I noticed it today, after losing constantly to players 200-300 points weeaker, and probably not winning a single raid on me since I got to ~1800 cups range, I got several wins today.
I check Aegir - and his mana is now average, from slow.
Judging from my ~40% succes in defence instead of ~5%, it seems like a good buff so far. You still need to sport healer next to him but whatevs, might consider telescopes on him now. Thanks SG !