Follow Your Passion: A Seamless Tumblr Journey
Halfas can't die because they're half ghost, so normal stuff can't kill them. But they're also half human, which means ghost specific methods don't work either.
Fun fact: ghosts have death scars.
Fun fact: just because they can't die, doesn't mean they're unmarked.
So, Danny learns this on accident when he goes to visit Frostbite about all the scars he's been getting from Vlad’s Plasmius Maximus.
And Frostbite is horrified by the assortment of Death Scars on the Great One.
And then he learns that Phantom is still a newly dead *baby*.