Amphibious. The toad can breathe air and water.

Standing Leap. The toad's long jump is up to 30 feet and its high jump is up to 10 feet, with or without a running start. 

Natural Camouflage. When this toad stands still, it is indistinguishable from a natural boulder.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 17 (2d10 + 6) piercing damage plus 5 (1d10) poison damage, and the target is grappled (escape DC 15). Until this grapple ends, the target is restrained, and the toad can't bite another target.

Swallow. The toad makes one bite attack against a Medium or smaller target it is grappling. If the attack hits, the target is swallowed, and the grapple ends. The swallowed target is blinded and restrained, it has total cover against attacks and other effects outside the toad, and it takes 10 (3d6) acid damage at the start of each of the toad's turns. The toad can have only one target swallowed at a time. If the toad dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 5 feet of movement, exiting prone.

Rock Throw. As an action, the boulder toad can use its tongue to grab one of the stones from its back and hurl it at an enemy. The enemy must make a Dexterity Saving Throw (DC 15) or take 4d10 bludgeoning damage and be knockedprone. On a successful save they take half as much and are not knocked prone.

Multiattack. If the boulder toad managed to bite and grapple a target it can immediately follow up with a swallow as a bonus action. (2 /per combat).