I use a farming team since last year.
I began with:
v1: Abhorath/Alchemist/Valkyrie/Banshee
But in Warlord 2, Banshee’s damage is too low so I changed for Keeper. And yes, the cascade provided by Alchemist or Valkyrie are enough to fill Keeper’s mana.
v2: Abhorath/Alchemist/Valkyrie/Keeper
But in Warlord 2, even Abhorath is killed too easily. So Kaya adviced me to replace Alchemist by Green Slime.
v3: Abhorath/Green Slime/Valkyrie/Keeper
I will surely come back to v1 or v2 as soon as I unlock Abhorath’s 2nd and 3rd traits. But, if you play in Normal or Hard I think v2 is enough: less Keeper but more golds with Alchemist’s spell.
For the ones that don’t have any legendary, I advice v1 team with Treant instead of Abhorath: you use all mana colors and Treant’s traits are quite tanky. Moreover, you can do extra turns with Treant’s skill (very rare but can happens 
). And, no more randomness ;-).