a comment I read today made me think of collecting some more advice for new Abyssian Swarm players.
I start with some stuff I got from another player:
Keep your Swarm safe in the early game.
Don’t keep it too safe where your Swarm can’t back you up.
Don’t empty your hand too quickly.
Cards like Plasma Storm, Homeostatic Rebuke, Tempest and Sunset Paragon can potentially wipe your entire board and you’ll be screwed.
You can spam a your hand a little to burn their removals.
If you want to spam your hand a lot, get some solid card draws.
Most of the time, don’t keep your Wraithlings at 1/1 because of cards like Ghost Lightning, Blistering Skorn, Krater and Spirit Harvester
that can also wipe your board.
Split your Swarm. Of course, you don’t have to always split them.
There are some cards with non-global Area of Effect that you should be careful of. Here are some cards that I can think of.
Try to look out for mana springs that are close to your opponents. They might accelerate their mana for removals.
(Neutral) Frostbone Naga, Riftwalker, Sunset Paragon, Deathblighter
(Lyonar) Holy Immolation, Sunriser
(Songhai) Flamewreath, Eternity Painter
(Abyssian) Necrotic Sphere, Grasp of Agony
(Vetruvian) Zephyr + General’s BBS, Bone Swarm, Lost in the Desert, Stars’ Fury, Wildfire Ankh
(Magmar) Makantor Warbeast
Board formation should be diagonal or some units that are at least 2 spaces apart.
Units should not be adjacent to one another.
(Lyonar) Aperion’s Claim
This spell works in a 3×3 area. Do not cluster all your minions in that area or at least not 2 minions that you want to keep alive.
(Vetruvian) Grapnel Paradigm
Minions should not be in a single row.
Minions should not be in the same column as your general.
The positioning of your Bloodtide Priestesses is very important. If possible you always want to have them perfectly surrounded by your own minions.
Swarm Abyss requires you to read your opponent a lot. You need to sense when a board wipe is coming, and commit to board accordingly. It can be tricky trying to use just enough resources to warrant an AoE card without running out of steam. (As @boronian mentioned, draw cards help, such as inkling surge, replicant, bloodbound mentor etc.)
Also, choose your win condition wisely. A Soul Grimwar will be more potent against Vaath, while Deathfire Crescendo could be tough for Reva to beat.
Speaking of Grimwar, feel free to pre-equip it. You might not be able to stop a board wipe, but you can stop it from feeling good.
Proper use of demonic lure is crucial. Depends on your list but generally speaking lure is the only removal you run because it is the only one that can still compete in the meta. It is a incredibly efficient and flexible card, but think about whether the threat is really worth luring. You only have 3 copies of the spell and the chances of getting a second one is much lower than the first.
For instance if Kaleos opens with a scroll bandit t1 and do you wraithling swarm and lure the bandit or play another 2 drop/combination of 1 drops instead? Killing the bandit asap prevents them from pulling any shenanigans with it immediately but if they stick a threat like say a flamewreath or something you can’t lure anymore then you might have just lost immediately, whereas letting the bandit off could’ve been salvageable otherwise.
Another thing is that any mana spent on lure means mana not speant developing/setting up your board. The trade off is something to keep in mind since ideally you use the 2 mana to kill something that could’ve destroyed value beyond that investment.
Finally, lure can also be used to reposition out of reach minions to give your swarm something to kill itself and proc effects off of for lethal in certain board states.