Being a self-taught true mage with very little knowledge outside of tier three, had always been a problem for Lith. He had to make up from scratch most of his spells, and not having much free time, if not none at all, his toolkit was quite limited.
For such reason, most of his spells were derived from imitation. Phloria's Full Guard, the Ry's slipstream effect or the Wither dark aura were all tricks that he had picked up along the way.
His fight with the plant Abomination had allowed him to further understand darkness magic, and how to overcome its obnoxious limitations.
Darkness was an element capable of inflicting an enormous amount of damage overtime, and to add insult to injury, it was extremely hard to defend from it. On the other hand, though, darkness based spells were so slow that outside niche situations they were nigh useless.