There is in fact such an action:
PROTECTING THE PRINCIPLE
Interrupt Action (–5 Initiative Score, 1 Edge) The character can choose to move up to 2 meters to place themselves between an attacker and a target and take the brunt of an incoming attack. There is no Defense Test (Reaction + Intuition), only Damage Resistance (Body + Armor). This action can only be performed once per Combat Turn.
Composure test:
8d6t5 4So, yeah, Succubus pretty sure bites it against 12+11 DV
Soak:
8d6t5 3that leaves 23-3-12=8 damage overspill that could bleed through to the Nightmare
Nightmare
Edge Reroll:
19d6t5 4Turning this into a tie and therefore a grazing hit only. But the Nightmare is therefore really on full defense and loses 10 ini instead of 3