Mythic spell focus and rerolls

[Danit]

With mythic spell focus it can make the target roll twice and take the lowest save, how does that work with rerolls? Do you reroll the original roll which is 2 dice or just one dice?

[LazarX]

GM's call.

[Turgan]

I'd say the reroll takes the same penalties as the original roll, if nothing is specified further. But ymmv.