He can, thankfully!

(admit it, you wish you had this spell bad, don't ya?)
Negi thrust into Ayaka as hard as he could manage, until he felt an orgasm coming that even his spell couldn't stop. That was fine with him, though, as he looked forward to his first orgasm.

Negi: Ayaka....here it comes! muttering Mortuus sperma (deaden seed).

Ayaka: Oh, yes! Cum in me, professor!! Oooooo!!! Yes....! Yes!

Negi erupted inside Ayaka's pussy with the strength and volume of all the cumshots he never had, as well as the one he'd just held back, not to mention the one that would've come anyway. Ayaka screamed as the warm fluid slammed into her almost as hard as Negi himself. The **** and mental satisfaction pushed her into what could only be called compound orgasms, one overlapping the next.

Negi pulled out of her pussy, which now dripped two kinds of cum, and fell over onto the nearest desk, panting for air. Ayaka fell to her knees, close to passing out. She had had sex before, but nothing like that!

Ayaka: Negi....where did...you learn to fuck...like that?

Negi: I just....did what came...naturally.

Ayaka: And you came inside me! So, I guess that means i'm all your's, since i'm carrying your baby now. I swear, i'll be the best wife ever!

Negi: Let's not be hasty. Are you sure we just...conceived?

Ayaka: With all the sperm you shot just now? If we didn't, it'd be some kind of...magic or something.

Negi couldn't help but smirk. Ayaka got dressed and said she needed to go back to her dorm. She kissed Negi again and left.

Negi: Well, she was right. That WAS a date to remember. Problem is, now i've got the whole rest of the evening to kill. Maybe i'll look around campus for awhile.