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Enlarge Spell is a heroic tier feat.

Prerequisite: Wis 13, wizard
Benefit: Before using a wizard at-will or encounter attack power, you can choose to take a -2 penalty to each die of damage rolled with the power to increase the size of its blast or its burst by 1.
You can’t use this feat on a power that doesn’t roll dice for damage.[AP:125]

Update (4/9/2010)

In the first sentence of the Benefit entry, replace “an arcane” with “a wizard at-will or encounter.”