Can a hero use an ability that requires strain if said hero is maxed already, can they take damage to perform the ability when at max strain?
Maxed strain ability usage
"A hero cannot choose to suffer [strain icon] if the amount of [strain icon] he has
suffered would exceed his Endurance. This includes suffering [strain icon]
to gain movement points
or using abilities with a [strain icon] cost
."
I'd say no.
no they can't use strain voluntarily if they maxed strain. They can still receive strain in damage from things they can't control, like trandoshans relentless ability