It's me, again! (AST checkup)

[Veis_Alveare]

Synastry will also save you MP on heals, as its piggyback heal effect can be used like a stronger version of Largesse if the tank is taking lots of damage, or to spread the healing around without having to take extra actions or spend MP on AoE heals.

I'm fairly certain they nerfed the healing recieved bonus on Synastry so that if you cast a direct heal on the person you've targeted with it they don't recieve any bonus heal beyond the initial hit.

Also using ED on CD can once you're I believe 68 can reduce the CD of Lightspeed by 5 seconds. I honestly don't pay much attention to CD reduction, it may only be when ED crits or something like that, but it's defintely another reason to use it frequently.