Under-deeps second automatic-attack for minions

[Darksatin]

We know that : « any attack keyed to Dark-domains, Shadow-hold, or Dark-hold is a detainment attack against a minion company »

My opponent is a Balrog player and his company goes to Under-vaults. He enters the site. The second automatic-attack is : (2nd attack)-Opponent may play as an automatic-attack one non-unique hazard creature from his hand normally keyed to a Shadow-hold.

I play « Ghosts » from my hand as second automatic-attack.

So, it’s a detainment attack or not ?

I don’t think so, because it is an automatic-attack, but it is unclear….

[Bandobras Took]

Automatic attacks are not keyed.

The automatic attack in question merely designates what kind of creature card may be used to create the attack.

It will not be detainment.