Does the effect of Iris occur when you play it or when you attack?
Iris' effect looks at the game state at the time of the attack, not at the time when you play it.
Source: TPCi Rules Team (2014-01-02), TPCi Rules Team (2014-05-08)

Relevant cards

Note: All applicable cards may not be listed below.
BW10_101
BW10_81