When using counterspell stance, each spell countered drains a spell slot from the invoker, as a spontaneous caster would, eventually resulting in not being able to cast spells of that level. Meanwhile, the focus remains untouched.
I believe it is intended that invokers counter spelling should lose focus relative to the spell used, instead of the current behavior.
If this is not possible due to scripting limitations, perhaps we can add spell clutch on a ten minute cooldown to invokers when they get invoker adept. This would allow them to counter a certain number of spells per combat without allowing them to counter-spell forever without using any focus at all, and without preventing them from casting any spells at all. Perhaps it could even be a limited version that only restores one spell slot of each spell level.
