The user can channel/send their attacks/techniques inside/through earth/ground to hit from an unsuspecting angle. The attacks/techniques can be triggered when they make contact with their intended target or they are projectiles that are aiming for their targets.
Genryūsai Shigekuni Yamamoto ((Bleach) uses Ennetsu Jigoku technique to summon pillars of fire from the ground.
Dorma Anim's (Fairy Tail) Dragon Blast Eruption.
Jura Neekis (Fairy Tail) using his "Rumbling Mt. Fuji" to cause a massive subterranean attack.
Alm (Zatch Bell!) uses the Ganjes Neshiruga spell to make energy beams erupt from below the ground and attack.
Maruss' (Zatch Bell!) Eijasu Garon spell creates a chained metal ball to attack the enemy. Even if an enemy mamodo has strong defenses, as long as they only cover the land Maruss can have the chain travel underground to reach his target.