Comments of chapter undefined of Esper Harem in the Apocalypse

yk what i just realized rn. the diary that Rebecca has and reads that seems to tell her a lot about the future must have be written and given to her by Rudy and the last pages which I think says a big event will happen soon and then Rudy will eventually reveal everything to her then, that event must be him time traveling. i also feel like we will soon see the first chronological appearance of the demon, which could explain how or why she seems to be previously acquainted with Rudy and Rebecca, idk maybe, we'll see i suppose

Can someone tell me what summoning pens do? I’ve accumulated like 30k points so I’ve just been randomly blowing it on summoning pens but I don’t even know what they do.

thanks for the chapter