So I'm trying to build an archery centered magus using the myrmidarch archetype. The main relevant feature is ranged spellstrike, which allows the use of ranged weapon attacks to deliver ranged touch spells. While its not necessarily optimal, its got some cool flavor.
At 4th level, a myrmidarch can use spellstrike to cast a single-target touch attack ranged spell and deliver it through a ranged weapon attack. Even if the spell can normally affect multiple targets, only a single missile, ray, or effect accompanies the attack.
At 11th level, a myrmidarch can spend a full-round action to cast a spell that includes multiple ranged touch attacks and deliver more than one using ranged attacks. The spell must have a casting time of 1 full-round action or less. This functions similarly to the base ability of ranged spellstrike, but the myrmidarch can deliver a number of missiles, rays, or effect up to the number of attacks he could make with a full attack. Attacks beyond the first take penalties as if the myrmidarch were making a full attack. Any effects not used in the round the spell is cast are lost, as are any additional ranged touch attacks the spell would allow beyond the myrmidarch’s maximum number of attacks.
There are a few arcana which can enhance this ability, such as Reach Spellstrike (which lets you use melee touch spells with it). However, one has me a bit confused: Pool Ray.
The first part is fairly self explanatory: invest an arcane pool point into a ranged weapon and later unleash it to add a burst of elemental damage that scales with level (with the cool quirk of letting you use it after you roll but before you learn the result). The puzzling bit is the second to last sentence:
The magus can expend 1 point from his arcane pool as a standard action to infuse a ranged weapon with elemental power. As a free action while making an attack roll with the infused ranged weapon, after the attack roll has been made but before the results are revealed by the GM, the magus can release the charge and cause his attack to deal 1d6 points of energy damage (acid, cold, electricity, or fire, chosen when he spends the arcane pool point to activate this ability). If he misses with this attack, the charge is lost and the effect is wasted. If the magus has the ranged spellstrike class feature (such as through the myrmidarch archetype), he can use this ability with ranged spellstrike to treat it as its own ranged touch attack. At 6th level and every 3 levels thereafter, the amount of damage dealt by this attack increases by 1d6.
So what precisely does this do to ranged spellstrike? Make it a touch attack? It doesn't seem to be written very clearly…
I've just become aware of the eldritch archer archetype, which will probably suit my needs better. It has its own version of ranged spellstrike, which complicates the question. I'm curious as to the interaction with Pool Ray for this version as well:
At 2nd level, whenever an eldritch archer casts a spell that calls for a ranged attack, she can deliver the spell through a ranged weapon she wields as part of a ranged attack. Instead of the free ranged attack normally allowed to deliver the spell, an eldritch archer can make one free ranged attack with a ranged weapon (at her highest base attack bonus) as part of casting this spell. The attack does not increase the spell's range.
If the spell can normally affect multiple targets, only a single missile, ray, or effect accompanies each attack; if the spell allows multiple attacks and the eldritch archer can make additional ranged attacks as part of a full-round action with spell combat, one additional ray, missile, or effect from the spell accompanies each subsequent ranged attack the eldritch archer makes in the same round until all attacks allowed by the spell are made. Unused missiles, rays, or effects remaining at the end of the eldritch archer's turn are wasted.
When you have the Ranged Spellstrike class feature AND the Pool Ray Arcana, it allows you to treat the Pool Ray as a completely different ranged attack with its own attack roll and damage.
So on one attack you have your Ranged spellstrike which deals your ranged damage plus the effect of your ranged spell, and you also have a free action ray that you get by spending one point from your spell pool that can either target the same target or any other target. In short it's extra damage on the target you're hitting, or you can target something else with it as well.
As for the latter part, for any ranged spell that gains more rays as it levels up, such as Scorching ray or Magic missile, each individual ranged attack during that full-round action has an accompanying missile, or ray that travels along with it. If you have four magic missiles but only three attacks, the last magic missile is wasted.