It's the proc. The proc is delayed, if you have a jab on ur target, and the second to last jab might proc skoria, you kill your target, but since skoria still raining down on it's slow ass way from the heavens, it hits the target. Even if he's dead. It will work the same as if you are the one that died.
kinda reminds me of the "near death" achievment, where you can kill someone with dots, and be dead, and you still get the achievment. Since you're under 5% health
PC EU
vAA HM / vHRC HM / vSO HM / vMoL HM / vHoF HM / vAS HM / vCR HM / vSS HM / vKA HM
Its also nice when fighting mobs because it also does 5k aoe splash damage so even if that single target is dead you still can hit others that are alive