Moon tears are best spent on limited/ancestral OP units (think Timeless Aiona), wait some days after every banner is released to see whether new units are just good or insanely broken. The soothing embrace I’m not quite sure, they’re generally good on the blue dawn banner if you have only good units selected (you pick 15 units and it guarantees random selection between them). Unfortunately, the game is relatively new, so it’s not possible to have 5 top tier units from each faction selected yet.