Seeing you as you were sinking, Mamoru kept in mind that he's standing on top of a building and so there should be several floors underneath him. He molded some doton chakra and manipulated the rocks the building was constituted of in front of him and mid range where he firstly met his opponent. With this, Mamoru loosens all the rocks within range and caused them to come raining down on the floor right underneath Faust.
As Mamoru was now falling down aswell, he performed the snake hand seal and created a large volume of water from his mouth spilling it toward the ground and lifting him up into the air. He then rides the wave, allowing him to travel towards Faust at high speeds and attack.
However, right before the wave of water reached Faust, he took out several shurikens and threw them towards Faust. He then quickly expelled a rock golem from his mouth which he made drop down onto Faust like a bomb and crush him also breaking through the ground to floor underneath.
As Faust is running across the rooms, he hears the cracking of the roof above him and comes to a stop. Faust looks up to see the roof coming apart and then I focus my lightning all around me, the energy crackles around and as the roof falls the lightning crackling around me splits it up easily and leaves faust unharmed. He then slams the ground with his hands and channels the lightning through the rocks as the fall and reaches your wave, electrocuting it and then you. Using your stupid wave against you.
I then jump into the air as you fall electrified, and gather my fire chakra to my hand and I fire three fireballs from it, the fireballs are huge and they crash into you as you are falling. The fire sends you straight into the earth, you go crashing through another floor and as you hit the other the fire and you erupt into a geyser of flame. Faust lands on the rubble and runs to the new hole you created and looks down to see your fried body.