Are incapacitated powers mandatory?

Hey, got a quick question.  When a hero becomes incapacitated, are those powers mandatory?  Some of them say "One hero may use a power now."  But others do not say "may".

So here was the scenario.  The Naturalist and Omnitron X bite the dust.  This leaves Legacy and Tempest to battle the Matriarch in Insula Primalis.  The Naturalist makes all heroes immune to damage from environment cards.  Volcanic Eruption comes out.  Awesome!  Then during Volcanic Eruption, because of Carrion Fields, Legacy bites the dust because of toxic damage and slaying lots of fowl.  Tempest survives because of damage reducers, since he is the hero with the highest hit points all psychic damage from the Matriarch is soaked along with toxic damage from Carrion Fields.

So the question is, do I have to follow Legacy's incapacitated portion which states, "Reduce damage dealt by environment cards by 2 until the start of your next turn."  Or is it optional?  Because in this case with the Naturalist making Tempest completely immune to Volcanic Eruption, I would not want it reduced.  I looked through Spiff's clarifications but came up empty.

Tempest was victorious and I don't think it mattered too much, but I did wonder.

You only may choose one of the three options. If none of them are desired, you can choose not to use any of them.

Just going to echo what Ronway said but also add this, the naturalist only makes you immune to environment targets with his incap, things like the t-rex and the raptor packs, not the volcano.

Just throwing it out there.

Okay, thanks.  Definitely need to read a little more carefully.