kő kövön nem marad

Hungarian

kő (“stone”) +‎ kövön (“on stone”) +‎ nem (“not”) +‎ marad (“to remain”), literally “there won't remain stone upon stone”

(idiomatic) not a stone will be left standing (everything will be destroyed and torn down)
Ha az ellenség ideér, itt kő kövön nem marad. ― If the enemy gets here, not a stone will be left standing.