Godsworn Champions of Ruin

[Infernalslayer]

The Slaves to Darkness battalion "Godsworn Champions of Ruin"  has the ability "In your hero phase, you can pick 1 HERO from this battalion that is within 3" of an enemy unit. If you do so, that HERO can fight."

Can that Hero fight once again, later in the combat phase?

The core rules state that a unit cannot attack more than once during the same Combat Phase but the battalion allows the selected hero to attack during the Hero Phase.

[RocketPropelledGrenade]

Yes, fighting outside the combat phase is a straight addition.

[Oak7603]

Bear in mind that any buffs on either side, you or your enemy that would trigger in the combat phase don't count either as you would be fighting in the hero phase and not the combat phase.

[Infernalslayer]

That would be my interpretation as well, thank you both!!