Wall of Imperium

Earth Glide. The elemental can burrow through nonmagical, unworked earth and stone. While doing so, the elemental doesn't disturb the material it moves through.

Extract. The wall of Imperium sucks in willing creatures into it as it passes near them. Only 60 medium-sized creatures can stay inside at a time.  

Deploy. The wall of Imperium jettisons willing creatures inside it out within 30ft of it. 

Close/Shut. The wall of Imperium can open and close slots on its body to enable archers and spellcasters to shoot out from within or close to protect them from outside damage. 

The wall of Imperium can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The wall of Imperium regains spent legendary actions at the start of its turn.

Close/Shut (Costs 1 Action). The wall of Imperium takes the Close/Shut action. 

Move (Cost 1 Action). The Wall of Imperium moves up to its speed. 

Launch (Cost 2 Actions). The Wall of Imperium deploys willing creatures up to 60ft away from it.