Scoundrel is really only ideal for melee crit builds. For your mages, it is far easier to get high ground and put your points in Huntsman. Also, scoundrel is not particularly useful for crit 2 hander builds, as 2 hander provides a better damage boost.
In short, scoundrel is only useful for melee, dual wielding, critical builds. EVEN for scoundrels, you should be putting 10ish less points in scoundrel than warfare. For anyone without 100% crit chance, the gap gets even wider.
The stat priority simplified for maximizing damage:
2 handed warrior
Elemental skill or Warfare for physical > 2 hander & crit chance > Scoundrel
dual wielding melee crit
Warfare > Scoundrel > Polymorph
bow build
Warfare > Huntsman > Scoundrel & Crit chance
Caster build
Elemental Skill > Hunstman & high ground > synergy elements for muli-element spells.
There are break points, and there are variations, but this will get you to 95% of the maximum damage possible.
There is a calculator for all of it here:
www.irodemine.com/divinity2/damage.php
