I think u mean arcane barrage at the end. Yes, it’s as simple as that but spam it since the barrage needs to be queued in order to get the radiant spark buff. The timing window isn’t that tight but because it’s of critical importance that it gets the buff you should just spam barrage toward the end of your last arcane blast.
Regarding AoE, not sure what each says but roughly speaking…
4 or more targets with cooldowns its:
(AP or RoP) - RS - ToTM- AE - AE - Barrage - Orb - AB+Barrage
That last AB isn’t all that important (imo) and I think at like 7-8-9?+ or around there you’re supposed not do that last AB. Without cooldowns it’s as simple as AE until 4 charges then dump with barrage. When you get clearcasting you fire missiles. At 7+ targets you ditch the missiles. This is assuming you are running harmony.
AP - Arcane Power
RoP - Rune of Power
RS - Radiant Spark
ToTM - Touch of the Magi
AE - Arcane Explosion
AB - Arcane Blast
EDIT: after thinking about it a bit that last AB in the AOE rotation probably is worth quite a bit of damage. It’s an 80% AB buffed from RS and 35% from magi…though situationally I could see some circumstances where you might want to skip the AB beyond a high mob number.