Gronth shrugs off the surprisingly powerful blows, his common sense becoming blinded by his sudden fury. With a bloodthirsty shout, Gronth swings again at one of the zombies.

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Raging, so temp stats are: STR 19 + 4, CON 19 + 4, HP 16 (-9 = 7).

Rage rounds left: 6 (after this)

Attack - (1d20+5)[16]
Damage - (1d12+4)[12]

If the zombie is killed, I get a Cleave attack against the other:

Attack - (1d20+5)[21]
Damage - (1d12+4)[7]

As far as tactics go, while Gronth remains in his rage (a total of 7 rounds), he will continue killing zombies outside. When this ends, Gronth will retreat to the tavern and try to defend it as well as possible with his shortbow.