after testing cu's for a bit i really feel it has to be high hp+max hp regen+INT>STR (str already 600 on cu so work up 500ish INT for better mana regen) to try and stop the healing sink BUT I also don't like the thought of not giving it a magic ability otherwise I feel you should run a Lion/sabre tooth tiger 4 slot with healing and be mounted. Also it looks like Cu will always try bleed before anything else and if the target isn't bleeding it will attempt bleed soon or immediately, if you go to trog cave with a cu these mobs will bandage themselves and you'll see the cu spamming bleed quite often. also against energy vortex's it won't go for bleed realising it's immune, i see a mana sink tho with it having low wrestling as it's attempting to heal itself but keeps getting interupted so goes to try again so it that theory 120 wrestling cu + discorded target should help it a lot more to conserve mana and get the healing off.
Giving it a magic ability you have the issue of needing 600 points (including 120 scroll) + 500 for combat skill 120's so essentially you have only 1900 points to play with.
Imma try a cu with poison breath then save enough points for disco to see what that's like as i heard poison breath is excellent, also bladeweave and crushing blow for specials, crushing blow on discorded targets might be decent + 10 mana save a cast.
edit - on second thought conductive blast over bladeweave or crushing blow improving it's auto's + you spamming lightning/enegry bolt on the target probably better option + it won't cast 2 special's together.