Earth Destruction Wave Technique

Chi Hakaiha no Jutsu (Earth Destruction Wave Technique)
Ninjutsu (Doton) [Earth]
Rank: 9 (A-Class);
Range: Close (10 ft. + 5 ft./2 levels);
Area: 10-ft-radius burst;
Duration: Instantaneous (see text);
Saving Throws: Reflex negate (see text);
Chakra Resistance: No;
Chakra Cost: 9.

This technique can only be used on firm or soft ground. With this technique, the user is able to part the earth and create a deep and dangerous hole. If this technique was used under a structure, it suffers 80 points of damage. This technique creates a 10 foot wide hole that is 5 foot deep per level of the user, maximum 100 feet. If the technique is used under a creature, it must succeed a Reflex save to avoid falling down the hole and suffer falling damage. The earth will return to its original state after 30 minutes, instantly killing any creature still in the hole (no save.)

Mastery
Every step of mastery in this technique decreases the time until the earth returns to its previous state by 3 minute (unless specified otherwise when performing the technique) and the damage dealt to structures by 10.