Target: each creature in the area of effect
Attack: Intelligence vs. Reflex
Hit: "1d6 + Intelligence modifier fire damage.
"Level 21: 2d6 + Intelligence modifier fire damage."[PH:159][Dr401:53]
Scorching burst is an at-will power available to wizards at 1st level.
The "Class Compendium: The Arcanist" article in Dragon 401 added the evocation keyword to scorching burst.