Q1 : do effigy lvl10 and effigy lvl15 have higher different. is it wise to sacrifice the circle for diev for utility ?
Q2 : how do DE combo with pandemic? for instance when the mob is hexed and DE and pandemic spread it, will the duration of the spread mob is the original duration or the remaining duration (with DE duration)?
ans much appreciated. sorry for bad english 
A1: 15% ish dmg difference, diev1 isn’t worth it for yourself on such a build. (Bokor2 isn’t to sp intensive, laima is nice but there’s better 1 circle support/dmg options. It’s also unneeded if you grab pardoner1.)
A2: DE used before pandemic works wonders, but pandemic cannot spread every condition. (hexing/vapor does work, incin does not.) Due to the short range it can be tricky to get DE’s full effect on incinerate for every mob.
i thinking of several build ,focusing on pd2
1: cle2-bokor3-oracle-pd2 (juz for fun due to oracle mechanics)
2: cle2-bokor2-diev-oracle-pd2 (similar reason xD)
3. cle2-bokor2-diev2-pd2 (more reasonable thinking)