Saru-Sichr is already knew as a great weapon because of the DoT : every instance trigger on a new apply of the DoT, that mean at less on graze.
But the effect is a melee weapon effect, the DoT roll cause the Mage Slayer 's Spell Disruption on apply, so 100%chance to fail with spells with two strikes.
Also, each new instance proc a lightning from Avenging Storm, as you can see in the combat log below. This is the first strike i made on Birta (l. 6), followed by the first DoT apply (l.5), then HbD (l4), new DoT (l3), Swift Flurry (l2) and the last graze from DoT (l1). And Avenging Storm proc 6 times.
I tried also vs a cre_dummy, to see the effect more later, and when there is 10 ticks already active, a new hit cause 12 lightnings. Etc.
Edit : the multiple Avenging Storm proc from SF/HbD , but twice because of the DoT rolls.
Of course that doesnt work against poison immune enemies, but it is really strong.