18 (natural armor)
76 (9d10 + 27)
30 ft.
Perception +4
bludgeoning, piercing, and slashing damage from nonmagical weapons
poison
charmed, paralyzed, petrified, poisoned
darkvision 60 ft.
Terran
7
While the rumbledum remains motionless, it is indistinguishable from a normal boulder.
As long as the rumbledum is in contact with the earth and has at least 1 hit point, it regains 10 hit points at the start of its turn.
If the rumbledum moves at least 15 feet straight toward a target and then hits it with a slam attack on the same turn, the target takes an extra 9 (2d8) bludgeoning damage. If the target is a creature, it must succeed on a DC 17 Strength saving throw or be knocked prone.
The rumbledum can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 22 (4d8 + 3) bludgeoning damage plus 4 (1d8) thunder damage.