Ranger Question

Ok, as I understand it the rangers expertise skill only lowers energy costs for ranger skills, and for attack skills. My question is, do attack skills include attack spells? I am making a ranger/necro and was wondering if spells like life siphon or vampiric gaze would be effected by expertise, or if it was just physical attack skills that were effected, anyway if anybody could clarify this for me I would appreciate it, thanks!