More precisely here:
QUOTE(Tenboro @ Feb 1 2011, 16:18)

You're probably doing it wrong. Coalesced Mana and Channeling both use the same probability, factored from Staff Proficiency, and is always between 10% and 35%. (You can see yours on the Equip screen.)
About nerf:
QUOTE(Tenboro @ Aug 20 2009, 17:13)

- Deprecative magic proficiency now has a larger effect of the effect of Nerf, particularly the defensive reduction.
QUOTE(Tenboro @ Nov 20 2009, 09:46)

Nerf is mostly balanced against the X-Nerf you get on level 200, so its main function is increasing how much damage monsters take as well as reducing their chance to evade and resist. The effect on rating isn't very high. But either way, the numbers it uses aren't very useful for a tooltip, since you're just gonna go "ok, and that does what exactly?".
This post has been edited by cmdct: May 31 2011, 07:55