Can’t find a new player guide, so I’ll just draft a quick one for you.
So, first of all - one-ofs are genrally bad, you only run “tech” cards as one-ofs, so avoid doing that until you are completely sure of what you are doing. You want consistency, so you want 3 copies of cards you want to see multiple copies of each game, 2 copies of cards you want to see from time to time, and 1 copy of cards which you want for specific match-ups. The exception to this rule are cards which you want more of but do not have. Include what you have and find suitable replacements for the copies you lack.
Secondly there are some cards known as “staples”. These cards are so good and have such a variety of uses that they have a place in every deck, except extremely gimmicky ones. In Abyssian that would be Daemonic Lure, Kelaino, Reaper of the Nine Moons, and Spectral Revnant. These are amazing, and no matter what you build, you will need them. For Swarm, I would also consider Ritual Banishing a staple since its the best form of removal avaliable to the archetype. Also, for Abyssian you need x3 Shrouds - 100%. With the lack of infaction dispell you need a way to deal with all of the diapellable threats like obelysks, Krons, overbuffed Kara minions, etc. You’ve gotten this part right, but you need to replace the missing staples with something of similar usefullness. I would replace 2 missing Revnants with Dancing Blades since that card provide amazing tempo. Kelaino can be replaced with Healing Mystics for now - you want a lot of cheap minions and Mystics are actually very good. Reapers are not really replacable, just get them when you get a chance. Also, Saberspine Tigers. You can never go wrong with the tigers. Otherwise, everything seems fine on this front.
Moving forward, something you seem to understand pretty well is a win condition. In your case the win-cons are Soulshatter Pact and Void Steal. Later down the line, I would suggest running Deathfire Crescendo, but for now those two are fine. I would run at least 2 copies of Void Steal - the card actually provides amazing utility, as well as being a win-con. You need to make sure that other cards you play are good with these two. I would cut Sphere of Darkness in favor of another form of card draw. Ruby Rifter and Stormmetal also seem out of place in your deck. I would consider adding Blood Baronettes, since you will always have a lot of wraithlings and once you get one of them buffed with something you will be able to capitalize on that. Another phenomenal card for any kind of swarm deck is Shiro. If you have multiple bodies on the board - and you genrally will - it generates a disgusting ammount of value.
Finally every deck need some form of card draw. Your does not seem to have enough. Abyssian has ultimate card draw spell - Rite of The Undervault. You would usually want 1-2 copies of it in your decks. Spelljammers, Soujourners, L’kians, and Golden Mantellas are other forms of card draw to consider. Remember, you can replace, so everything putting random stuff in your hand acts as pseudo-draw.
Considering everything above, I would make something like this:
Work for more Spectral Revnants first, then Reavers and Deathfire - those cards will buff your deck a lot.
I hope, I didn’t miss anything - I’m kinda wasted and sleepy.
Anyways, you have the right idea - keep it up! Hopefully somebody who is actually good at Abyssian will also show up to help.