Possible bug: Gains a frenzy charge for each 25% life lost

The "gain a frenzy charge for each 25% life lost" ability on mobs seems to be checking only when the mob is hit by a new attack. I don't know if this is intentional behavior.

If I poison a mob down past each 25% threshold, it gains no frenzy charges until I hit it directly with an attack, at which point it will gain all the frenzy charges it should have. (e.g. if I poison it down to 20% HP then hit it with my normal attack, it immediately gains 3 charges).