[Mardagg]

Abysia has been my favorite nation in Dom 2.
While MA Abysia lost a lot of its appeal now in Dom 3,partly due to the introduction of old age(which I personally hate), I still think they do reasonable well...but i wouldnt recommend it for beginners since many mistakes can be made.

Basically, there have been 2 ways i played MA Abysia in MP games so far:

1.Soul Contracts

MA Abysia is perfectly suited for Soul Contract spamming.
I prefer this a lot compared to concentrating on Blood instead.
generally other blood nations tend to outresearch you in that area so that u have no chance to get some uniques,which are a main reason to rush for blood first.Furthermore,construction synergizes a lot with MA Abysia.

Those Demonbreds are simply great all around commanders,with no old age problems AND they make the perfect leaders for your devil hosts....this is a big differnce to LA Aby,which lack fitting commanders and are therefore not equally suited for sould contracts(though still pretty nice),especially early on in a game.
Take for example an awake Blood Fountain with 6Blood ,leave out the 1 Fire path to get 1 more scale and just empower the Fountain after 10+ turns to Fire 1...you dont have much need for Fire gems early on anyways.Concentrate your research on Construction therefore.Those fire lanterns for research are as much needed as the soul contracts.If you do it right,you can already build 1 or 2 contracts within the first year with this strat and in addition you got pretty nice scales as well to afford building up 1 or 2 more starting armies that can easily beat most indies.
Its not exactly turtling that is needed here.
You can also make the fountain dormant to gain even better scales,but this comes with quite a bit of drawbacks and delays the contract production quite a bit.
Only recommended with CBM mod though,since only there the Fountain has got some really nice things.

2. rushing strat

RUSH your opponents.Dont care about mid/endgame.Just try to conquer the map.
I think many people underestimate the Early game options you got with MA Abysia.

-You a got extremely strong starting army.
-You can field quite a lot of smiting mage priests early on,use smite for small enemy armies and with Fire 3 even fire darts become pretty good early on vs larger armies.I dont care about low precision here early on.u still kill a lot of troops and friendly fire is nothing to fear due to fire immunity.
-You can crank out Assasin scouts like crazy as soon as you got 1 or 2 more castles.Most people underestimate how good Assasins can be in Early Game and Mid game.Use them as scouts and to kill indie commanders.Then switch to do surprise attacks on human enemy provinces(yes.2-3 slayers have no problems with low to med PD) or to assassinate enemy commanders.At early to midgame,killed commanders can mean a lot to every player.
-Lava Warriors crush everything that you might encounter early on...when played with some decent blessing and mixed with Shield wielding troops as arrow fodder+placed properly.Sure ,u take losses,but when played right,u can afford it.
-5 fire gems per turn is a nice boost to your gold income when alchemized...that extra income is a nice early game boost.

There are several different ways to play a rush tactic with it.
You can,e.g., take a dormant Fire 9 or Fire 6 Blood 4 Solar disc.
Strengthening your Lava Warriors,who wield 2 weapons and as such profit a lot from Fire/Blood blessing.

Those magic paths still allow for pretty good scales,something along: Order 3,Prod 2(u need it when rushing,since capital troops are important);growth 1-2(normally 3 would be nice here,but when trying to rush,its not that important anymore),Heat 3,Luck 0,Magic 1,Dom:6-8
On what to concentrate research on,should be pretty obvious when going with the solar disc: Evocation.

Turn1:

prophetize assassin.He is the one to single handedly take down tough indies at start.Script him on Smite,Smite,Smite and you kill even knight commanders in your first battle like 90% of the time,depending a little on your blessings.Kill all commanders and then move a scout to take the province.
Build anathemant dragon to lead your starting army.
Build some more Heavy Infantries with no shield.
Patrol home province with starting army,set taxes to 120-130.

Try to get a second army composed of Heavy Infantries no shield and some Lavas,lead by a Dragon as fast as possible.
The reason I first concentrate on those heavy infantries without shields is because they are better when mixing actual squads with Lava`s,since both got around the same combat movement and then the berserker morale from the lavas gives a nice boost to the whole squad.You will take losses with Aby and morale can be an issue otherwise.This is the reason as well why i dont focus on demonbreds early on.U cant mix them with lavas due to speed reasons and ive had severe morale issues with these guys in important battles at early game stage during test games.
Later on you should switch to form whole squads of Shield wielding infantries and the lavas form there own squads behind those guys.U need some time though before u can do that well.

try to get a second and third castle up very fast.If necessary skip building lava warriors for some turns to get some money in,if alchemizing fire gems isnt enough.
Try to build those on provinces with surrounding mountains,so that you get high resource production.
Second castle is for Heavy Infantries,third castle for spamming slayer assassins.Nice thing about the slayers that u dont need to build a temple or Lab in that castle,since the commander spot is taken away anyhow.That way u can use that money for other things early on.Always renember: Slayers are much,much stronger than regular assassins and can be produced everywhere( i wish machaka`s assassin would be as well),they are a unique weapon Abysia possesses,something other nations dont have and as such,should be played accordingly.
If you have been lucky with a lot of resources in your home provinces due to surrounding mountains,you can go first for slayer spamming in castle no 2 .
All can be done within the first year ... by late at Turn 15 you should have 3 castles up,otherwise u did something wrong or have been very unlucky.
At that time,turn 12-15,u do have alot of power to attack other human players already.Use it!

I dont have the time to go into further detail here,but i hope u at least get the idea.

Ive been very succesful using both of these strats in expert only MP games.