Orc tracker's total pain?

[Metathron]

I've been puzzled by this for some time now and haven't seen anyone mentioning it, so I'll just go ahead and ask:

What is the deal with the orc tracker's summons taking damage out of nowhere (well, the tracker waves his sword a bit)? In the battle log it says "Total pain does .... damage, ... snakes died".

The only explanation I can think of is that the trackers' adrenaline went down a level and so the number of snakes adjusted to the power of the talent? But hmmm that doesn't feel right, aren't snakes a level 1 adrenaline summon anyway?

EDIT: Or do their numbers decrease as the orc trackers themselves die? If so, that's a bit of an odd effect.