Lvl 13 Attack Powers +Metamagic 4e

[HMS Invincible]

What is better: Prismatic Spray or Orbmaster's Umbral Assault. I have the orb class feature, so I can extend either blind ability. How important is the damage boost and bigger aoe? I'm conflicted since both are pretty hot looking, unless I missed something in the other powers.

P.S. There's a feat in the Quintessential Wizard that says you can spend a healing surge to extend a duration of a spell for a turn. So I can blind someone almost permanently, depending on how many surges I can spend.

[Yakk]

Prismatic Spray doesn't have a blind ability? Oh, you mean "Prismatic Burst"?

Prismatic Burst is an encounter power, not an at-will. Read up what the orb mastery gives you.

Burst is radiant, hits will, and is a 5x5 area for 3d6+int damage. It also only blinds targets hit.

Orbmaster's Umbral Assault is necrotic, hits a 3x3 area for 1d6+int damage. It creates a zone that blinds things within it. On the 2nd turn, it expands to 7x7 and doesn't blind your allies (when you extend it with your orb), but still impacts enemies and only within the 7x7 zone.

The burst one doesn't play as well with enlarge spell due to the large number of small dice.

The Wizard book you mention is a 3rd party supplement, I cannot comment.