The magma golem is so fun to use with the adramelech warlock! I have a book made and it has had fiar success. Not all of my plays have been wins, but the golem has played a big part in the games i did win!
The book is on the forums as Adramelech's Golem
I would say go with the magma golem over the fire elemental. the golem has no upkeep, does not have a weakness to fire, and has a cheaper mana cost. And some lower level demons will help keep some of the pressure off of the golem, for sure, but I would run at least 2 little guys and at least 1 other heavy hitter.
I have found that fireweaving off the golem is fantastic to stack burns! but i recommend adramelechs touch on the golem. That way if the burn added during the upkeep rolls a zero, it does not go away and you can still fireweave it that turn. Having the armor drop on the golem is the biggest weakpoint in my opinion. slow hurts, but sometimes you just want him to walk into a zone to apply burn damage during upkeep. That being said, if you go up against a siren, or really any mage in general, watch out for acid balls and rust. Since a burn stacks on him every upkeep, having 1 to 2 corrodes on him on top of that can really suck! Rust is the biggest issue. At least with actual corrode markers, you could keep him out of the way, let burns build up, or fireweave them to the golem, so that his armor drops to zero and the corrodes get removed. Siren also has easy access to water spells but that shouldnt be an issue if they are used mainly to extinguish. If they are up the pressure so she uses them on other targets. If they go after the golem, up the pressure so they have to focus on the mage!
Against a priestess, if you can get multiple burns on her or another creature and she is using her full action and mana to get rid of them, that just gives you time to capitalize and put more pressure on her. If she is using her quick action to get rid of them, you should be able to stack them faster than she can take them off. The holy school also has buffs against nonliving and such...for those I just say deal with them as fast as you can :b lol
A marked for death on the enemy with the adramelech warlock using a magma golem and firebrand imp with demonic link is glorious! the imp is cheap but with those bonuses he is going to be a big threat!
just with those cards, the golem would roll 6 dice 6+ burn 10+ 2 burn , the imp 5 dice 7+ burn that heals your mage and the imp, if the target is burned, every attack, and the mage 3 dice 4+ burn base attack
hope this helps