Flash allows you to normal call the unit at any time you can make a choice, or in response to an effect that would affect your own cards. This includes, but is not limited to:
The ride step, while you are choosing a card to ride
The stride step, while you are choosing a card to Stride
The main phase, as normal
The attack step, while you are choosing a unit to attack with
The guard step, during the battle that your unit was attacked
In response to an ability that would retire or bind your rear-guards
As usual, cards with Flash can only be normal called from the hand. However, if a card with Flash can be normal called from a zone other than the hand, then it can be flash-called from that zone as well.
