This Noctilith Crown was on display at Warhammer World.
Towering over the battlefield as dread monuments to the Dark Gods, Noctilith Crowns are brutal edifices raised up by Chaos Space Marines to tear open the fabric of realspace. Forged from noctilith—the esoteric, warp-conductive material commonly known as blackstone—these towering structure-crafts act as vast psychic resonators, channeling raw immaterium and thinning the veil between dimensions to deadly effect. By siphoning and amplifying chaotic energies, a Noctilith Crown creates a localised reality-bleeding field that empowers Heretic Astartes sorcerers, shields nearby Chaos infantry behind flickering warp-barriers, and severely destabilises enemy psyker abilities. Standing as an unyielding focal point of ruin, a Noctilith Crown ensures that reality itself buckles beneath the weight of the Warp, carving a permanent foothold for daemonkind and chaos legions alike.
Though from a game mechanics perspective this is a force field, to me it looks more like a gateway in a similar manner to a Stargate.