In a recent Preferred Enemies episode, a listener asked whether or not you have to declare you're using your serpent shield ability when you shoot with the serpent. The hosts landed on the decision that you do because the serpent shield rule is worded as...
...In your shooting phase, a wave serpent can discharge its serpent shield in its shooting phase by...
Basically, they decided that the phrase
"its shooting phase" indicates (or at least implies) that the decision is made when you've "activated" your serpent to do stuff.
If that's the case, I've been playing the rule incorrectly for a while. To my mind, there's no such thing as a "personal shooting phase" for each unit. The wording is weird, but my take is that "its shooting phase" is just meant to indicate the controlling player's shooting phase. I.e. it's not a shooting attack, but you can't suddenly opt to use your serpent shield's offensive rule during your opponent's turn.
Thoughts? I'm inclined to start treating the shield as basically a shooting attack (needing to be declared when I declare my shooting) just to be on the safe side.