The answer was no, Nova Spells weren't the cause of the gap between the tower Lith had used back at the Feymar mines and the one in M'Rael's hands.
The problem was that even when Lith still had just a blue core, he had fought alongside Solus, not against her. No matter how many opponents they faced, he took care of the physical aspect of the fight while she dealt with intel and spells.
Solus was the one manipulating the tower and operating its enchantments. She was the one collecting the data from the Sentries and filtering only the relevant bits.
M'Rael, instead, was doing it all on his own. The tower was actually several times stronger than it had been at the Feymar mines. It had recovered many floors, the Eyes, and the Mouth.
Yet M'Rael was but one elf and there was a limit to what his focus could achieve.