Colour Spray
School illusion (pattern) [mind-affecting]; Level sorcerer/wizard 1
Casting Time 1 standard action
Components V, S, M (red, yellow, and blue powder or colored sand)
Range 15 ft.
Area cone-shaped burst
Duration instantaneous; see text
Saving Throw Will negates; Spell Resistance yesA vivid cone of clashing colors springs forth from your hand, causing creatures to become stunned, perhaps also blinded, and possibly knocking them unconscious. Each creature within the cone is affected according to its HD.
2 HD or less: The creature is unconscious, blinded, and stunned for 2d4 rounds, then blinded and stunned for 1d4 rounds, and then stunned for 1 round. (Only living creatures are knocked unconscious.)
3 or 4 HD: The creature is blinded and stunned for 1d4 rounds, then stunned for 1 round.
5 or more HD: The creature is stunned for 1 round.
Sightless creatures are not affected by color spray.
Extend Spell (Metamagic)You can make your spells last twice as long.
Benefit: An extended spell lasts twice as long as normal. A spell with a duration of concentration, instantaneous, or permanent is not affected by this feat. An extended spell uses up a spell slot one level higher than the spell's actual level.
So, is Colour Spray extendable, or not? If it is, the flash of colours is presumably still instantaneous it's just the effects that last twice as long.