Wiktionary
a. Contextual comparative. Modifies another adjective (to which the "so" is a direct anaphoric reference), indicating a greater degree of the quality in question.
Usage examples of "more so".
She was beginning to hate the place, all the more so because of the contrast between its present abandonment and the way it must have looked when Kathleen occupied it.
They were humanoid in form, more so than Mahnmut, but not really human in appearance.
The illusion was surprisingly convincing, and would have been even more so if I hadn't felt my real legs to be in a slightly different position than those of the mannequin.
Knacks were thick on the ground here, much more so than any other place that Peggy had visited.
The dream had been deeply disturbing, more so than any of the other crow dreams.
The passionate pair in love's embrace are at least equally willing to postpone the stabbing, if not more so.
We plan for her to leave Westfaire, which is conspicuous now and will be even more so, and go to another place, a hidden place where she is unlikely to ever encounter the Dark Lord.
There are many choice-thefts less heinous than his, and only a few more so .
This was some heavy kind of real life, and it hurt like a knife blow, even more so because the glass shards were breaking my skin as I pressed myself into the floor, seeking relief.
Apparently, when things got to that point, he'd say something like, 'My dear, there's nothing I'd like better, truly, but I must tell you that I have a very savage and jealous mistress who if I so much as dallied with you, would cut my throat in bed or stab me in my bath (he was quite a bit like Marat, you know, Franz, and grew to be more so in his later years), besides dashing acid across your lovely cheeks and lips, my dear, or driving a hatpin into those bewitching eyes.
I was still very cold, more so because of the inactivity of sitting in the boat while another rowed.