Fear of death must've been used.
This begs the question of why WWW3 would be a target.
How are you so sure? Mafia might find it more convenient to use the Fear of Death on somebody else to take down two birds with one stone. Especially if we're talking about a role of sorts.
That, or there is also the possibility of Fear of Deceit having been used. Which would partly answer your question, if the latter was true.
I'm assuming that mister internet cubed used his own ability on himself, given his "wait what". If he did, then fear of death is the only possible way he'd be ded.
On top of this, fear of death simply says "Your target dies, no matter what." It says nothing about additional kills, and neither does the fear of nothingness. The fear of nothingness could've been used as it ambiguously may bypass NKs, but we know mister internet cubed died, so that's unlikely.
And fear of deceit... It says nothing about lying about the nightkill and it'd be bastard if it did, so let's trust the honourable mod and hope it isn't.
So. Who wants to volunteer their own death, kiddies?
