I've been thinking about what Astrologian used to have lately and had a thought for a new spell after seeing a now removed thread detailing someone's surprisingly good ideas for healer reworks.

How does this sound for a capstone spell based on the current seals system (I MUCH prefer 3.0 and 4.0 Ast but rip)

Almagest: Cast time 2.5 seconds. 25Y range, 6Y radius. Does 650 potency to the first enemy and 400 potency for all remaining enemies.
Effect: Damage over time potency 55. Standard duration 12 seconds.
Effect: Increases remaining duration of allies beneficial effects (buffs) by 12 seconds
Seals bonus:
Every Solar seal extends the duration of the damge over time by 6 seconds
Every Lunar seal extends the duration of ally buffs by 6 seconds.
Every Celestial seal grants a shield equal to a 250 potency heal