Lets get this back on topic please.
this sounds like a nasty side effect of a crabbed hero getting spectraled. however it does make sense to me.
spectral causes a hero to attack their own team.
crab causes a hero to attack their own team until they fall off and die - essentially meaning they are on the opposing team until the crab falls off, so spectral would choose them to possess if their intellect is the highest.
when the crab falls off the possessed hero returns to your team but it is stil possessed, going back to spectraled heros attack their own team
you need to be careful about who you choose to go against a crab- best bet is to choose a tank that has a low damage output like horse or bro, bulwark doesnt seem to get crabbed at all or send in a sacrificial tank that you dont mind losing.
But most of all- do not -send in someone that could wipe your whole team with high damage