Mythic Arcane Cannon and multiple energy spell

Question

If I cast mythic arcane cannon and use its conducting ability by casting a spell with multiple energy types say shocking grasp that's been metamagiced to do half electricity and half fire. What does the cannon damage become?

If the half is split between the energy types, it would be 3d10 normal and 1d10 electricity and 1d10 fire (due to pathfinders rounding down).

If the half is equally given to both "other half is energy damage of the spell’s type", it could become 3d10 untyped and 3d10 electrical and 3d10 fire.

But which choice is the correct one when a spell has two (or more) energy descriptors?

Answer 1

You're applying "half damage" incorrectly. Elemental Spell specifically states

split the spell’s damage, so that half is of that energy type and half is of its normal type.

Damage is not the same as damage dice. To find the damage of your Arcane Cannon, roll all 6d10 dice. Divide the result by 2 to find the untyped and energy damage. Divide the energy damage by 2 to find the electrical and fire damage.

Your maximum lost damage is 2 (for a number such as 31, where halving it loses a point and halving 15 also loses a point.