Here is another installment of exTRAPaganza, our Thursday over-the-top trap series.
The ceiling of this temple is made of huge blocks of stone. Whenever a treasure inside the temple is disturbed, a slab falls on the spot occupied by a random character. This character must make a hard Dexterity saving throw or take massive bludgeoning damage.
Additionally, when n+1 slabs fall (where n is the number of party members) the last slab blocks the exit. So unless the party has other ways out, they are trapped forever.