I'm pretty sure Zelretch can just cut the entities off completely.
He mastered the Second Magic and basically made it.

The entities actually overpowering him in usage is impossible.
The Root powers his ability, and with that, he has infinite power and is actually using the power of a god compared to insects.

Kinda amusing as a crackfic, but is internally inconsistent enough to contradict itself(not even Nasu lore, but itself) at every turn.
Zelretch being a conglomerate of every single random thing in existence(pissibly including a kitchen sink Zelretch) in one paragraph and then, in the next one, lamenting how Entities exist outside human logic and so nothing can be done in time with their barriers sounded particularly dumb.

Hmm.

Short. Not bad. Idea feels complete enough.

entities use second magic like Zelretch.

Zelretch trying to use himself as COUNTER GUARDIAN, fail. Bring in Emiya, success? Don't want to think too hard about how Zelretch managed to do that to himself, Nasuverse mechanics feel like rule of cool.

Bring in shirou, to assist Fortuna. He did not really add to the story. It is an excuse to involve him.

Bit short. Any fight with non jobbing Entity or totally paralyzed entity with you having path to victory would logically be short, though.

timelines don't match up; but second magic covers time travel, doesn't it? Don't know how it and fourth magic overlap.

conclusion: not worth favoriting, but works as a short thought one shot. maybe it will inspire other fics.

oh my. Oh Myyyyyy.

Interesting... I kinda want to see how that would effect Skitter's path though...

The absurd alternate Zelretchs were funny as hell!

Interesting. I can’t wait to see more. Please keep up the great work!

Love the fic, though I am sad the post-UBW Shirou left Rin in this.

NICE! Very nice. Please continue this!

ngreaigdpraishgrhaewogi that was awsome

Yes. Just yes.

Where is Scion?

mfw Jack Slash gonna be a hero

keep up the amazing work

Hmmmmm thats great nice