If you use Mastermind on a character with Impervious, do they get to roll to reduce damage to zero?

Yes they do.

Impervious
When this character is dealt damage, roll a d6. On a result of 5 or 6, the damage dealt is reduced to 0. On a result of 1–4, the damage dealt is reduced by 2.

Mastermind
When this character would be dealt damage, you may instead choose to have all the damage be dealt to a single adjacent friendly character with a point value less than this character's. Any additional effects of the damage dealt (knock back, penetrating damage, etc.) are applied to the character taking the damage. Damage dealt by this power is not an attack.

Just Seconding W.I.T's answer. Yes, they would roll for Impervious

It's not from an attack but it's damage dealt, got it, thanks guys!

...even better, MM to the Blob.

Not much betterer if it's 2 damage

Or 1 damage.

W.I.T. nailed it. I'll just add if the damage being masterminded is penetrating you'd not get to roll for impervious.

Actually, you still get to make the roll (as you might when using Dr. Manhattan or WL Superman), but the penetrating damage would not be reduced no matter the result.

(grins) In which case Dr. Doom simply chooses to soak up the damage with his Invulnerability.

I love Starter Doom.

There are two ways to read this question.

If you use Mastermind to move damage TO a character with Impervious, the answers above are all correct.

If you have Mastermind on a character that also has Impervious, you cannot both use Mastermind and Impervious on the same damage. You either use Impervious or you attempt to move the damage to another figure with Mastermind. You don't get to roll-reduce and then move the reduced damage over.

Who doesn't?

But seeing Incap on the opposing team always makes Doom a little nervous as his Mastermind is of no use against it.

And Mind Control

He could do with a bit less Pulse Wave around for that matter.

But those are just the little flaws that keep the cries of "cheese" at bay.

Yah, but EW and PB won't affect the Blob, so take that. A MM'd 5 damage Psi Blast on your imperv guy is still 5 damage, Blob takes 1.