That gets explained after the kiss.

After a moment of maintaining the kiss, Linze broke it, blushing, but smiling. "So what about the seventh type of magic?" Touya asked, holding up the last stone.

"That would be the non elemental, or as some people call it, Null magic," Linze explained.

"What incantation do I use for that?" Touya asked.

"It has no set incantation," she explained, talking about how Null magic had different spells that didn't fit any of the elemental categories, but could do various things. However, even those who could use Null magic couldn't use all the spells, usually they could only use one Null spell, though a rare few could use multiple, and Elize could use a physical boosting one, and there was also one called warp, just to give Touya an idea on how varied the effects could be.

"So how would I even know I had an aptitude for any Null spells?"

"Well, the stone changed in your hand, so it's clear that you do," Linze replied, smiling. "Sometimes the name of a spell will pop up in your head, but if not, you can try a few random spell names to see if they work."

He decided to try the warp spell, finding that one to be a particularly useful concept. Just walking to the forest took hours, so... "Gate," he intoned, and a portal opened up.

"Whoah, you got a good one to work!" Linze said, running up to it, and they both stook their heads through... To find and scare the living hell out of Elize in the forest, and causing her to fall on her ass.

"Wh-what the hell?!" she demanded in shock.