Massacre is a M Brute Action - Attack card from Flesh and Blood (Armory Deck - Rhinar, ARR).
M
Armory Deck - Rhinar (ARR)
Card Text
When you attack with Massacre, if you have discarded a card with 6 or more {p} this turn, Massacre gains +2{p} and intimidate.
If Massacre is discarded to pay the cost of a Brute attack action card, intimidate.