
FraVit |
Hi Moonheart, I'll try my best to help you with a build.
Spellstrike would rarely be used in your early levels but this will solve itself at lv8.
Suggested Trait: Magical Lineage(Shocking Grasp)
Highly Suggested feats: Steadfast Personality, Spell Penetration, Greater Spell Penetration, Spontaneous Metafocus, Intensified Spell, Empower Spell, Maximized Spell
Build Example: Dex > Cha > Cos > Wis > Str = Int
Eldritch Scion(1): Weapon Finesse
Eldritch Scion(2)
Eldritch Scion(3): [Magus Arcana] Familiar, Dervish Dance
Eldritch Scion(5): [Bonus Feat] Intensified Spell, Steadfast Personality
Eldritch Scion(6): [Magus Arcana] *
Eldritch Scion(7): Spontaneous Metafocus
*Prescient Attack if you want to build towards Maximized Spellstrike feat, Arcane Accuracy if you don't.

Moonheart |
Hi Moonheart, I'll try my best to help you with a build.
(...)
Thank you, those idea were appreciated and helped me to brainstorm the thing. Writing a little update since the campaign is now at like half of its content and my Magus started to take off.
I found that clinging on metamagic for an Eldritch Scion is not that a good idea. The scion has very specific and different things to do, while metamagic will cost him extra fees largely putting in question its worth.
I've chose to build a kind of switch-hitter Magus.
It plays with Desna's Shooting Star, allowing him to rely only on Charisma... that's like +7 to attack rolls, damage rolls, spell DC and arcane pool by level 8.
That weapon allows him to use the Throwing Magus arcana, which make the character regenerate her arcane pool points spent during minor encounters. The build then arrive to the "boss room" with her full arcane pool (11 points, which is a lot)
While its only metamagic is the Enpowered Magic that is used against bosses only, the fact the character has high chances to hit and pass saves, on top of his high amount of arcane pool available still make it a MVP during major encounters. :)
Eldritch Scion(1): Divine Technique - Desna's Shooting Star / Bloodline Familiar: Youn Wyrd
Eldritch Scion(2)
Eldritch Scion(3): [Magus Arcana] Throwing Magus, Precise Shot (EIR)
Eldritch Scion(5): [Bonus Feat] Quick Draw, Steadfast Personality
Eldritch Scion(6): [Magus Arcana] Empowered Magic
Eldritch Scion(7): Combat Casting
Eldritch Scion(8): [Magus Arcana] Hasted Assault / feat
I use a Backblink Belt to deal with multi attack problems with throwing weapon and to not have to pay for the benefits of Throwing Magus.
At level 9, my Arcane Pool is 11, and I can regenerate 7 more points by throwing my weapon at people's face.