Lagartha was a wood-element user. She manifested thick, green plant vines that sprouted from the ground.
These green vines acted like pythons and approached the snake sisters. The vines wrapped themselves around the snake sisters before pulling them away from their positions, just in time to dodge Eren's attack.
Boom! Boom! Boom!
Eren's summoned beasts detonated themselves and lighted up the night like some festival of light and fire. The mana fluctuations they caused spread along with the light tremors their detonations had caused, creating clouds of dust all over the terrain.
Shifa and Vihah would have been in a critical situation if they had stayed at their positions only to get bombarded by Eren's attacks. That's because Eren had used all his summoned beast for that one attack, which also served as a smokescreen for Mia.
Lagartha placed them beside her on either side by controlling the green vines before focusing her gaze on Mia.