Siphon bullets make enemies invulnerable when their health is reduced below 0

[FaxMeDarling]

When i drain an enemy's health by killing them enough times to reduce their max hp below the range of a siphom proc, i can no longer kill that enemy. It seems it first applies siphon, then checks for damage, and i guess things that have 0 or negative hp just can't take damage.
Could it be that if siphon reduces the enemy below 0 and damage is clamped to never reduce the characters below 0 hp. As a result enemies take 0 damage while having negative hp and i guess skipping death checks?

 

[FaxMeDarling]

Ok, so, I cheked, it seems that it only happens when the enemy took 0 damage and has negative max hp. Realistically this should not happen, but i think it may be possible with someone like victor or viscous that can easily heal. My guess is that damage is stored as an integer, so it's x damage taken vs max hp. While damage is at 0 and max hp are negative some check fails and the character doesnt take damage at all. If the enemy with less than 55 hp takes damage, then is killed with a siphon, it goes under 0 as base max hp and is absolutely immune to every form of damage.

 

[max36]

I managed to (accidentally) replicate this with the Seven standing in the atrium. Siphoned 12 Stacks.