Thx, missed the formula and was pretty confused by the numbers.
Actually I just wanted to find out on what it procs and at least i got that.
The Proc rate is ok, the mistake was that I counted doubleattacks as 2 hits, but i guess NB cant proc of the second attack

.
Nevertheless, NB procs of
- successful melee attacks (not doubleattacks)
- Procs when the Proc effect says "inflicts xxx melee damage on target" (Planar Orb of the Wanderer, seems to only proc once for the 3 attacks)
- CAs which say "inflicts xxx melee damage on target" (Nature Blade, Primordial Strike, and the int one)
Procs for 6.4 times per minute with 8 AAs (32%) (Thx Ahl)
i.e. ~9.5 secs GroupHeal for 312 (crit 405) => 2,9 k Groupheal/min (up to 17.7k for whole Group/min) => 49-296 BASE HPS