What does Dazmand's Spotlight Moment do?

The window is short: five seconds from the start of the fight, and only one skill. If you spend those seconds moving or attacking normally, the free cast is gone and his skills cost EP as usual.

So open with Dazmand's most expensive skill, and do it immediately. The EP you don't spend stays in the pool, and the whole party draws from that one pool. That makes the saving more useful in a team that already burns energy fast. Irisalis has high EP consumption, and Scorchhowl's play style revolves around charging attacks and keeping its energy up. Somni Wing works on the same problem from the other side: it raises the active Aniimo's EP recovery, and its trait adds 10 to the party's maximum EP while it is in the party.

The page on party loadouts and shared energy covers how the pool works across your team of four.

Not settled: The exact trigger is not settled. One version of the trait describes the start of combat and another describes Dazmand entering the field, so it may not reset when you swap him in mid-fight. Some descriptions also make every skill in the five seconds free rather than only the first.