I'm not saying it stacks (with itself, as when another human casts it, you mean?), I'm saying it scales. I'm not sure how much, but it should be at least +3 per stat by the end game, possibly more.
I agree it's not very exciting. But it is decent.
You're right it scales. Lvl 21 it's +3 strengh, finesse, int and +5 constitution (not sure why more in con).
I still don't like it tho. Even if it's good.
