I have been testing balanced builds and have raised a character over the week with 1,960 strength and 2,466 magick with gold heaven's keys. Would the magick add to the strength when i'm in close combat and say if i doubled up conquerers periapts with demons that would also contribute to the damage output
Yes..... only if that weapon has a magic component to it. Your Heaven's Keys daggers are perma-enchanted and deliver both Str and Mag damage, so your Mag stat will effect it.
Mag stat will have no effect on weapons that deliver only pure-Str damage.... unless those weapons get a temporarily elemental buff from a magic user. I cannot recall how much Mag damage they then do. But this effect lasts only as long as the buff.
For your second question.... Yes. Using +Mag and +Str boosting items (periapts or group potions) will effect either (or both if you use both types) of damage. As an example, when my Arisen fights as a Mag-based Ranger with a perma-enchanted longbow, I use both Salomet's Secrets (+Mag) and Taglius Miracles (+Str).
You vacuous, toffee-nosed, malodorous pervert!! GT: Dr Nick 1971
The two damage stats do different damage; they're not stacked together. That means if your character is powerful enough to break both damage thresholds, it can and will do so.
Conqueror's Periapts would affect only your STR portion of damage output while Demon's Periapts will affect the MAG portion of your damage output. Accordingly, Tagilius' Miracles and Salomet's Secrets do the same thing, respectively, but for all party members rather than just affecting the individual popping the periapts.
Oh thanks guys didn't realise there were other consumables that also effect the party aswell even though i'll be mainly playing solo unless i'm taking other peoples pawn out i'll take it all into consideration :)