User blog comment:StrategicMagic/Carry by Proxy - Why (Some) Assasins Don't Fall Off Late/@comment-216.36.26.248-20121207075153/@comment-216.36.26.248-20121207080341

One addendum: To get that kind of burst out of LeBlanc, you need to use 383 AP at level 18 without counting your E. Cassiopeia using just her Q and E on a single target will do puts Cassiopeia at a sustained 800 DPS.

Counting LeBlanc's E (hitting for both initial and secondary damage), you need 246 AP, which puts Cassiopeia at sustained 685 DPS with just Q and E.