I've finished Elysium this morning. Strangely, I haven't had any problems with Cerberus. I mean, with all of the bosses, you can just combine Hero Strike (damage), Second Wind (heal) and Fury of the Bloodline (some damage, but crucially it refills 3 adrenaline bars). Other than that, I tend to mostly keep my distance and maybe get in a few melee whacks in opportune situations or do a headshot with the bow (for better effect, use special arrows, such as the Death Arrows of Artemis). Battlecry of Ares is also good for dealing high amounts of damage, plus you can't die while it's active, but I haven's used it much (I only got it when I unlocked the upgraded version in Elysium). Side note: this part seems to be throwing even more ability points at us than the previous one. I guess it makes sense if those are to be used for boosting individual stats by 1% per point, although I still haven't spent any on that. I have more abilities than I can map instead, as well as some 30 unused points.