Meteor Swarm Trap (4e Trap)
From D&D Wiki
A magical object taking up one square, such as a rough stone pillar with a meteor mounted on the top of it, which causes fiery orbs to rain down from above, shrieking loudly as they fall. They smash into their targets, obliterating them in a storm of fire and scorching the ground. Once the pillar is destroyed the meteor will fall and crack, harmlessly shattering into pieces of rock. Players can make an Knowlage Arcana Check, DC 30 to identify it when they see it. Being unable to move, it has a low reflex and is easy to hit, but being made of stone means it is hard to land a damaging hit against that defense.
This could be used in an encounter by positioning it so that players are within range while fighting monsters, making the encounter more difficult as they must try to avoid the Meteor Swarm attacks. This would work particually well in combination with monsters that are immune to fire damage, as the burst will not affect them.