Outside the building Stonebreak the treant smashes into the walls.
Attack 1: 1d20 + 14 ⇒ (1) + 14 = 15
Damage, Crit 19+: 2d6 + 15 ⇒ (3, 4) + 15 = 22
Attack 2: 1d20 + 14 ⇒ (6) + 14 = 20
Damage, Crit 19+: 2d6 + 15 ⇒ (3, 6) + 15 = 24
Damage is doubled against objects but the first attack misses with a 1 so 48 damage