Meteor Shower

Spell. Create a Meteor Shower at target foe's location. For 9 seconds, foes adjacent to that location are struck for 7...91...112 fire damage and knocked down every 3 seconds.

Spell. Deals 7...91...112 fire damage and causes knock-down every 3 seconds (9 seconds). Hits foes adjacent to target's initial location.

Progression
Fire Magic Fire damage	0 7 1 14 2 21 3 28 4 35 5 42 6 49 7 56 8 63 9 70 10 77 11 84 12 91 13 98 14 105 15 112 16 119 17 126 18 133 19 140 20 147 21 154

[edit] Acquisition

Although there is immediate visual indication of rocks hitting the ground, the first damage and knock down event does not occur until 3 seconds after the spell has been cast.
- Since the earliest knock down occurs after the first 3 seconds, it is recommended that foes are snared when the spell is cast.
If knock down length is increased to 3 seconds (from Earthbind or a Stonefist Insignia), then foes will either be knocked down two times with a 3 second delay, two times with a perfect quarterknock, or three times with two perfect quarterknocks.
Be wary of foes using this skill against your party, especially if it is composed of mostly henchmen and heroes, as they will all stand in approximately the range of the attack (unless you order them to move), devastating your party.

The Guild Wars 2 Wiki also has an article on Meteor Shower.