You forgot the next part:
He was using these deaths to replenish his own well of hatred. The dark side ate people from within, but while it did so, it gave them much too much power.He appeared to have more power than she had. More power than Luke.
There's also this:
She raised her head. She was stunning, he had to give her that, with her bright green eyes, and red, almost auburn, hair. A woman to respect. A woman that no one ever should tamper with. "I haven't felt power like this since Palpatine in the early days. If this continues, Han, Kueller will be stronger than the Emperor ever was, and he'll do it quicker.""So you're not here for Luke after all." She swallowed. "It may be too late for Luke. I'm here for the rest of us."
Spirit Kun > Kueller ~ (or close) Sheev > Luke
The only thing one can think in the face of something like this is "Darth Malak" 👆