try these
bonus bFixedCastrate,x; Increases fixed cast time of skills by x%.
bonus bVariableCastrate,x; Increases variable cast time of skills by x%.
bonus2 bSkillFixedCast,s,x; Increases fixed cast time of skill s by x milliseconds. (supports skill names.)
bonus2 bSkillVariableCast,s,x; Increases variable cast time of skill s by x milliseconds. (supports skill names.)
bonus2 bVariableCastrate,s,x; Increases variable cast time of skill s by x%. (supports skill names.)