Moloch is a lot of fun to use, but I tend to only keep him in defend teams. The further you go into higher levels the more stats everything has causing Moloch to take longer to be effective. Having 3-4 cursed troops on a team also tends to be just as effective as a single Moloch due to the initial burst it has from the start. I have a couple different builds with Moloch, but none of them I ever use unless I just want to mess around.
Jarl Firemantle *** or Mercy ***
Fun to watch 3x suppression. xD
3x silence immune with a lot of true damage and mana drain.
And the following 2 for defend teams:
Jarl Firemantle ***
Inferno King ***
This last one I do tend to use as my defend team in occasional rotation with a few others. It is pretty weak in this current version because a Gorgotha or Inferno King summon does more harm than good, but the team will be quite effective whenever the devs rebalance summons.