There is potential for what I am tentatively calling a
'blood mage' healing spec if you go down the Night Blade Siphoning skill line and spec heavily into max magica.
Funnel Health, and
Soul Siphon both provide self and ally healing and
Sap Essence gives a small AOE ally heal. Combine this
Leaching Strikes , Resto Staff
Quick Siphon or
Siphon Spirit, and
Essence Drain for both ally and self heals on hit, and you are looking pretty good.
If you wanted a little more self healing there is also
Degeneration in the Mages Guild tree. Alternatively you could take another Resto staff ability for better party heals (and to lvl the skill line up). To be honest you would probably switch these around depending on the situation and play style.