User blog comment:TAGDavid/Demon Construct/@comment-26069426-20150817150643

This is what I notice:

You play 3x impact, but they're bottlenecked. They depend on having 1 of 4 cards on the field. I would either play Brave Equipment, Glory Seeker at 4 (total 8x weapons), or remove the impact altogether, freeing up 3 cards for better options.
 * Impacts

As I said above, you can either invest in more weapons, or you should switch things up. Staff of Monster Master, Alerta gives you a great defensive option. Or Dominion Rod can give you a great Aggro/Defense mix.
 * Items

That being said, I understand the choice for Alcsbane... you want the gauge. My understanding, however, is that Alcsbane is meant to buff Dungeon Mix. I think the previously mentioned weapons are more directed options for Dungeon Enemy's playstyle.

Pillar of Fire for Dangerous Fuse. You'll likely have a monster in center if you go the Alerta route. Cecilia's Spell Disarm for Smile Charm to keep your resources up, especially since you're vulnerable to lifelink.
 * Spells

For the monsters, the biggest problem I see you facing is a lack of consistency. You're only commiting to, like, 3 or 4 monsters. The rest of scattered 2-ofs.
 * Monsters

Mazubaha for 2 more Keith. Maybe try to fit in Jade Golem, Shyatan? Steel Golem, Futoff is a good target for Agos Marh, but my problem with him is that he's only a 7k butt. It forces a link attack, which is good, but with only 4 spell nulls he's likely dying (plus, some decks plus on a link attack). And Alerta can only get him to 9k... Demon Lord, Joker Grunwald may be splashable.

Iron Golem, Nasr at 4. One Gauge Demon at 4. Evil-Break at 2. Gummy Slime is good side-deck. It'll help you match up against engines that require moving or bouncing.

I would take out Deukruzar. Death Master, Lelag Monarch could be a good alternative, since you're playing 8 size 0s. It might also be a good idea to splash in some Dragon Tooth Warrior to stave off the lifelink hit. And if you have 2 in the drop, you're kinda giving Monarch 2 soul. With Demon Lord's Dungeon set, you'll be able to pay 1 gauge at the start of your turn to call back the Dragon Teeth... Another option could be Diamond Golem, Fluud. He's a pretty large Tangler with a Lifelink 3, but has a construct attribute. His soul is part of his cost so tapping Marh for Fluud is a misplay, but viable when going for game.

Synopsis is: if you're going to play defensively, you've got to have a larger barrier to your flag than just a single size 1 monster, or Shalsana. You need to throw more into the mix to control/stop your opponent's efforts. Not sure if the answer is what's listed above, but I hope it's a good place to start.