Once it resolves, you add one red mana for each card in an opponents hand, that mana sticks around through phases until the end of the turn, and then Inspiring Refrain resuspends itself with another three time counters, letting you cast it again later
You may play them this turn.
Even if that creature is legendary, the Spirits would not enter the battlefield attacking
Its attacks are nice for game introductions: its first attack, Trinity Charge (for two colorless energies) only has the effect of attaching up to 3 energies from your deck for your Pokmon-V in any way you want
Of course this is easier said than done, and Amazon is banking on that, so a bit of discipline is needed to profit from this deal
You can also bring back Wastelands to keep blowing up your opponent's lands and lock them out of the game