All Out Attack (5e Variant Rule)
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Named after the combat mechanic from the Persona franchise.
An all out attack can only be initiated when an enemy is surrounded by PCs in melee range and is unable to move in any direction. A PC must use their entire turn (including action, bonus action, movement, etc.) to initiate the All out attack. All PCs surrounding the target will then roll for the damage dice for their currently equipped melee weapon as they savagely attack the target on the initiating PC's turn. This is a very powerful mechanic that is advised to use with caution.