Diablo 3 patch 2.6: new legendary off-hand: Iron Rose
This is a new legendary Necromancer off-hand (Phylactery) added in 2.6.0.
"Attacking with Siphon Blood has a 40–50% chance to cast a free Blood Nova."
With perfect roll 50% chance, it is a free Blood Nova every 2 casts of Siphon Blood.
However, according to the first half of the video, it did not do much, if any at all, damage even though Trag'Oul set was equipped (which gave 3300% damage to blood skills). Then I added the skill Blood Nova to the bar. All a sudden the Blood Nova proc deals big damage buffed by Trag'Oul. Looks like a bug to me. Hope Blizz will fix it.