As I have an E³ in the works myself:
how is elec mastery?
I'm planning for AoE immob, second ST hold, the lightning field (slotted to drain even more end), and the chain heal.
Is the chain heal any good?
(building a troller without the AT... and with built-in status protect)
I've never really liked the Blaster masteries even with the villain side patron pools.
(For some weird reason I very often end up in teams that are trollers+domis only, or teams that are blaster-heavy with no tanks or healers).