Kelnin's dome can push players through the map.

[Armroker]

Essentially, when the expanding dome pushes the player and if the player hits a wall or other surface, there is a high chance that the dome will push the player through that surface. In the clip, Talon hits a pillar, and the game pushes him under the map. Casting Dome directly above the player's head will push them down under the map.