Mana users are rare and dangerous ones are extremely thin on the ground. That's maybe one encounter in fifty where Mana Clash might be nice but ten times as many where those wasted spell points hurt.
A soloing mage has a lot more headaches than spell points to address them, so it's always a balancing act. For example, Ajira lost three hostile deshyrs to kill-stealers because she didn't have Blood Wound, and she had to opt for the easier 'inside' version of the Kolgrim fight because at that time she just didn't have the firepower to solo the 'outside' fight with the all the trimmings (including that blasted fire-proof drake).
Of the things ahead, Denerim calls for Blood Wound because it's the only way to get a perfect score during the mass encounters with friendlies (Sgt. Kylon, and the hostage thing for the Crows), and the same holds true for the dwarves you have to rescue from a darkspawn horde, and the Roadside encounter with the three bumbling suicidal mages who pick an unwinnable fight with a group of darkspawn. Plus Civil War, and the Refugees thing.
On the other hand, Redcliffe urgently calls for Combat Magic, Earth Quake and maybe even a healing spell, and it will be blastedly difficult even so. Something will have to give here, and the count of lost kills will probably rise in any case. I've already lost one friendly - a werewolf during the Zathrian fight - and I have no intention of losing any more if I can help it.
There's just no space for luxuries until the Redcliffe/Landsmeet bounty of extra spell points rolls in, and even then there's better things to get. Like Shock/Tempest or Entropic Death. None of my solo mages has ever taken Mana Clash because the number of actual problems it solves is almost zero. Same for Spell Might. Or investing into WIL instead of MAG outside of a no-pots run, for that matter. Wasting spell/attribute points during a solo run pretty much invariably entails falling down on the job, at least with legit DAO builds. Judging by the numbers you posted in the other thread you seem to have lost/ignored some five hundred kills, despite the broken respec mod you must have used. And how many friendlies fell by the wayside, I wonder? Be honest.