Im going mad here. I just cant beat Abhorath to finish the Karakoth quests.What do I do? I have googled it, but gotten nothing I can use to help me. Im only 36, so Im really new.I hope you guys have some ideas - and please write card names instead of what they are doing… since I dont know yet what they are all doing …
… Going nuts here LOL
Level up your hero, choosing brown and red masteries each time.
Eventually, this will unlock a weapon called Mang.
Use Mang with your hero, and you will eventually be able to one-shot Abhorath before he heals.
Hope that helps! 
There are troops who debuff the enemy, things like entangle, stun, freeze, etc. I know early on you may not have many of these troops, but they are how you can tip the scales in your favor.
As @Magnusimus said Mang is a great early weapon, it steals armor and gives it all to you as atk. Its a very powerful weapon.
One other thing to keep in mind when building a team. Four damage dealers is bad. You want someone in there who either destroys, explodes, or converts gems. These provide lots of mana for your damage dealers. They will allow you to fill quicker and take out a pesky troop before they can be a nuisance.
Literally any silence if your damage is too atrocious to nuke him early game. It’s not like he can hurt you besides skull like anyways!