Surtr's Menace

Surtr's Menace is a type B passive skill introduced in Fire Emblem Heroes. As the name suggests, it is exclusive to Surtr.

Overview
Surtr's Menace has a functionality similar to both a Wave and a Threaten skill. At the start of the turn, if there is at least one hostile unit within two spaces of Surtr, he gains a +4 boost to all stats for one turn, while all foes within the two-space area receive a -4 penalty to all stats in response.