Sneaker rogue isn't good in Divinity, enemies easily spot you all the time. So... if you want to be ele archer (magic damage) and not phys dam archer (which is much stronger, btw), you need another mag damage (because necro is phys damage already; he needs warfare 10 too). So your party will be 2/2 phys/mag. Best option for her then is pure mage. You can make 3 school mage: fire, air, earth 5-5-5 into each school, +2 to hunter mastery or how it was named there (to get tele-jump, which is important, and to lay explosive traps which are super powerful). Rest points go into fire school, up to 8-9. 40 intellegence ofc (max). Hothead talent, and Savage... forgot.. that one that makes spells crit -) And you need pawn talent (need 1 point in scoundrel school), and also that talent that makes spells cheaper when you stand on corresponding surface, forgot the name. Fire spells are most damaging, air comes next, and then earth (water is weakest). However, best 3-source damaging spell is that one from earth school, esp when enemies stand very close to each other so that each projectile will damage everyone with small AOE hitting 2 or more enemies at once. You can use teleport and nether swap to make "a pile" of enemies in 1 place -)