I'm loving this story, but I cant shake the feeling that something really bad is going to happen.

The filly’s face suddenly darkened into a cruel smirk,
“You’re Buck-Buddies aren’t you?”

I laughed so hard at this...

Personally, I don't care about grammar or spelling mistakes, I just say what I like and what I don't like. And I like your story enough to wait as long as you need to upload the next chapter. Take your time.

That said, I really like your explanation about the different kinds of magic. And Thank you for not using Discord's vines as the model for the tentacles. It worked pretty well with "Nightmare Moon's magic". If I would complain about anything it would be about the "cum om command" thing. Well... Just my opinion.

Looking forward for next chapter!

"Pump the next chapter out" huh?
Is that what they call it now-a-days?

(Tentacle Start)

......LET IT BEGIN......

A few hiccups in tpology

The demon in behind Twilight suddenly disappeared, and the unicorn fell onto the couch with a soft thump. Grumbling in annoyance she turned around to yell at the demon but shut her mouth when she saw the red sparkling cloud near the ceiling. It looked extremely similar to NIghtmare Moon’s transformation, and on second thought it was probably the exact same thing.
You have 'heavy' fingers. Capital N capital I in this case.

Two tendrils descended slowly, stopping right in front of her faze. They lazily swayed about, as if they were staring at her curiously. Twilight giggled and reached out a hoof curiously. One of them moved forwards to meet her and the unicorn giggled again once she touched it. The tendril was solid, and when it touched her it had a slightly tingling feel to it. The feeling spread through her leg, making her muscles relax slightly.
You meant 'face' not faze.

The combination of sensations for the mare was too much for the mare to handle, and she suddenly passed out without fanfare. The tendrils immediately stopped fucking the mare, and withdrew from her abused holes and gently deposited her on the couch. Carefully wrapping themselves from around her they placed her in a comfortable position.
The sentence in question is just a bit wordy. Perhaps something like:
The combination of sensations was too much for the mare to handle, and she suddenly passed out without fanfare.

Her orgasm triggered Asmodeus’ as pussy tightened immeasurably in its quest to milk the cum out of him. The demon slammed her down on his cock, hilting in her one last time before the first rope of cum shot out. Rainbow screamed again as she felt herself being pumped full of the demonic cum. The massive warmth of it pooling in her womb, filling it completely in the first shot. The two of them held each other in death grips as rope after rope of cum forced its way into the mare. The sheer amount of it caused a visible bulge to form on Rainbows abdomen. Eventually their orgasms died down, and the ponies muscles relaxed. Rainbow was delirious, reveling in the feeling of the mass of cum sloshing around in her.
I'm embarassed to ask this, but, who's pussy tightened? No one 'owns' that pussy in the sentence, if that makes sense?

You have little hiccups with punctuation, like here:
“What are you thinking of? Twilight asked the tendril in front of her, already knowing the answer. It moved forward and traced the unicorns jawline, Twilight could see the demon’s smirk in her mind’s eye. She rolled her eyes,
And:
Asmodeus’ cock suddenly hit a particularly sensitive spot in the mares snatch and Rainbow broke their lips’ embrace to let out a loud squeal of pleasure. Without missing a beat the demon began giving the mare small lovebites up and down her neck. Rainbow rested her head on the demon’s shoulder, shuddering in pleasure as the demon fucked her.

Overall, a rather enjoyable story.
Yes, I am glad to see that the Plunder vines weren't used as the model for the tentacles. That... Ick... Doing that would DEFINITELY involve like Dark, Gore.

3902697
I didn't see any problem with Asmodeus' application of the 'cum on command' thing. It was an example of Demonic magic. It's natural for him to do something related to Lust, which is what Asmodeus is a demon of. But, that's just me.

3906200
Yeah. Like I said, it's a matter of opinion. I think that it's a bit "cheap", but it's a bad word... I mean, I don't think that it was wrong in any way, but struck me as cheap because sex has a certain rhythm to it.

3902697
This is a little bit of a spoiler, but not really. I don't intend for anything bad to happen, this is slice of life for a reason. I envision this story, and the subsequent side stories and (maybe) sequels to focus on a "sexual revolution" of sorts in Ponyville. And i don't mean that the town becomes Equestria's brothel, if you get what I'm saying. I don't think there will be an overarching plot with antagonists and all that jazz. I already know where I want to go with this story. That being said, stories following this are considerably less thought out. So alot of things are possible.

And about the "cum on command thing" I used it as an example of demonic magic and that's all really is, i do not plan on using it as a cop-out in clop scenes in the future, so if you're worried about that don't be.

3903656
lol, didn't catch that

3903836

3906200
Awesome, I'll make sure to fix all those errors when I get to this in my re-work. Thanks alot.

3915313
Glad to know I'm doing something right

3906373
Yeah, I can agree with that. There's definitely a case of it seeming cheap, tawdry...

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When the devil did i hit the downvote button? Lemme fix that.

“Is ‘I got laid’ an acceptable answer?”

Yes, yes it is

only miff i have is alicorns being top dogs me i know were power lies with the apex pretitor that is a dragon

Silly spike. "I got laid" is always an acceptable answer

I really like the bit regarding how Chaos magic works. Totally adding that into my headcanon!

Also, is Twilight an Alicorn in this story? I don't remember any mention of her wings, so I guess she isn't...

“Is ‘I got laid’ an acceptable answer?”

There may be certain situations where it isn't but this isn't one of them all things considered.

3921240 dear Celestia. I love the pictures you use!!!

im seeing a trend here this is heading for a herd thing isnt it