Sure-Footed. The Abditosaurus has advantage on Strength and Dexterity saving throws made against effects that would knock it prone.

Living Bastion. If the Abditosaurus takes any damage from a critical hit, it temporarily becomes immune to critical hits for the next 3 turns. Both its turn and the turns of its opponent(s) count towards that number. The Abditosaurus still takes regular damage as normal, just not the additional damage from critical hits. Once the 3 turns are up, critical hits can once again affect the Abditosaurus and this special trait cannot be used again until it completes a long rest. 

 Crushing Collapse. If the Abditosaurus has been reduced to 0 hp, its massive body will immediately collapse to the ground. Any living creature within a 15 foot radius around it must make a DC14 dexterity saving throw, or they take 10d20 bludgeoning damage from the weight of its body crushing them. Any surviving creature(s) that took damage from the collapse of the Abditosaurus can make a DC 14 strength saving throw in an attempt to crawl out from underneath the body. On a successful save they crawl out into the nearest open space within 5 feet of the body from their point of exit. On a fail, they can repeat the saving throw at the beginning of their next turn successively until they are freed. 

Weighted Stomp. Melee weapon attack. +7 to hit, reach 10 ft., one target. Hit: 23 (4d8+ 2) bludgeoning damage. The Abditosaurus partially rears up on its back legs and then brings down both its front legs and feet in powerful stomp. 

 Low Sweeping Tail. Melee weapon attack. +11 to hit, reach 20 ft., up to three targets. Hit: 17 (3d8+ 3) bludgeoning damage. The Abditosaurus shifts its back haunches and then whips its tail low over the terrain towards its opponent(s). Each opponent within range of its attack must make a DC15 dexterity saving throw or be knocked prone. 

Forceful Tail Lash. Melee weapon attack. +8 to hit, reach 20 ft., up to two targets. Hit: 18 (4d8+ 1) slashing damage. The Abditosaurus places most of its weight on its front legs and then whips its tail towards its opponent(s) with as much force as it can muster. Each opponent within range of its attack must make a DC14 dexterity saving throw or be pushed/knocked back 20 feet.

Massive Frontal Kick. Melee weapon attack. +10 to hit, reach 10 ft., one target. Hit: 14 (3d6+ 3) bludgeoning damage. The Abditosaurus draws back one of its massive front legs and kicks out at the opponent unfortunate enough to be within its range. The opponent must make a DC12 dexterity saving throw or be pushed/knocked back 10 feet.