There's really no point to limiting yourself to only one or two types of magic, if you're putting the attribute points in intelligent you may as well put at least one ability point in each school so you can cherry pick all the best.
Also, using magic damage and archery/melee is often just waste of AP. You will do better stacking one stat for damage. Getting the base 8 int needed for all the nice magic buffs is certainly a potentially good idea for any build, but your damage should usually be focused on whatever stat you stack highest (dex for daggers/bow, str for general melee, int for magic damage). Especially since those stats will also boost relevant skill's CC potential and CDs as well.
You do not want to spread yourself thin. Focus on one main damage stat and deal damage primarily with the abilities it affects, but you can dip into other abilities for buffs and utility.
I'd say either dex or int are worth putting 8 points in solely for utility like haste and invisibility. A mage with rogue/ranger utility is nice, and a rogue or range with mage utility is also. Str however, isn't worth dipping into, you either go full melee warrior or you don't bother with it. You can dip into dex or int w/a strength build, but you should never dip into str with a dex or int build.
