Currently, the debuff states that if you use focus, you lose all focus. Fine.
But then you try to use Channel, which costs no focus but rather health, and on top of draining your health to convert to focus, the generated focus is wiped out as the affix thinks channel is using focus when it’s not. So you lose all your health and focus by using the spell.
This debuff is also pretty problematic.
There are several spells that function based on charging or timed consumption that are completely broken or rendered unusable by this debuff.
Take Frost Stream as an example, but you can use any of the sustained fire beams or other channeled spells.
Frost Stream takes 25 focus to even activate upfront, but needs to channel for at least a second to do any meaningful damage or build up. But the Pestilence debuff immediately interrupts Frost Stream as soon as you use it because it eats up the 25 focus cost plus all your focus, and the spell stops exactly the moment your focus goes to 0, regardless of what point of the damage channel pulse you’re at.
In other words, if I’m making an offering of 3 fallen embers for Plague Lv4, and this debuff appears, my weapon now effectively has a single usable spell, Homing Frost, or another high cost instant cast rune attack.
Neither Channel or Frost Stream are usable, removing 2 rune attacks from my weapon.
There is a similar echo buff function in the crucible where using a spell consumes all focus and buffs the spell in proportion to focus drained.
If this function is going to stay, then channeled spells need to be changed so they drain a set amount of focus upfront and have a set duration of channel instead of their current “hold to drain 25 focus per time intervals for x amount of time until you run out of focus”.