Item #: SCP-4971
Object Class: Cerrnunnos (Item can be functionally contained, but the Foundation cannot achieve this for logistical and/or ethical reasons)
Laconic Containment Procedures: Keep civilians away from the town in which it's located and station a ton of armed task forces around it. Shoot anything that comes out and hope that SCP-4971-▽ doesn't try to leave.
The "Cerrunnos" containment class has been created for SCP-4971 and denotes SCPs that technically can be contained, but shouldn't for ethics' sake. In this case, the fact that containment means performing a ritual by which most of the global population must be killed.
Laconic Description: SCP-4971 is an extradimensional forest located within an abandoned mall connected to Earth after a cult performed a series of rituals. Inside the space is an expansive forest filled with hostile humanoids with glowing triangles for heads. The Foundation sends in a few MTFs to check out what's inside, all of them get massacred by the humanoids or SCP-4971-▽.
SCP-4971-▽ is the god of sacrifices, Biphi, that lives inside SCP-4971. It draws power from rituals across the world, especially ones performed by its cult.
In the end, the Foundation can only pray that SCP-4971-▽ doesn't find a way to exit SCP-4971 and enter our world, otherwise there simply won't be any means of stopping it.
Additional Context: SCP-4971 was the first SCP to use the Cerrnunnos Object Class.