When can I use Scatterbug's "Abnormal Outbreak" Ability?
It's pretty clear. If you are not taking the first turn of the game, then when you get your first turn (i.e. the second turn of the game) you may use Abnormal Outbreak. This is the only turn of the game when this Ability may be used.
Source: Forbidden Light FAQ (2018-04-20), TPCi Rules Team (2018-05-03)

Relevant cards

Note: All applicable cards may not be listed below.
SM6_5