Summoning: Toad Stomach Crush is an offensive ninjutsu, a variation of the Reverse Summoning Technique. The user reverse-summons themselves and their opponents into the stomach of a giant toad, possibly of the same kind as the giant fire-breathing toad used in the Summoning: Toad Mouth Bind technique. Essentially, the battle is moved to a new battlefield.
The technique is similar to Barrier: Gourd Toad Prison, which is used to capture and isolate a victim: the opponent ends up trapped inside the toad's stomach, cut off from allies, completely immobilized, and the stomach crushes them to death, and even the unique feature of Pain's summoning could not help them.