Too few creatures. does nothing on an empty board, and Equipment-heavy decks run out of bodies. Aim for 15–17 creatures and take a playable Dwarf over a third or fourth Equipment, especially in pack 3.
Ignoring the . Dori, Ori, Óin, Nori and Thorin are , so you can only have one of each name on the battlefield. A second copy that enters forces you to put one into the . Two copies of a legendary common is fine, since one waits in hand as a backup. A third is usually worse than any other playable.
Taking cards over . Your Dwarves and Equipment bring the anyway, and most common and uncommon storied cards get only small bonuses from it (Ori, Keeper of Songs; Bombur, Gentle Dreamer; Dáin, Lord of the Iron Hills).
Equipping instead of developing. Equip costs are paid on your own turn and are often large (Goblin Plate Mail , Ragged Short Spear ). On turns 2–4, cast creatures first and equip with leftover mana. Put Equipment on Dwarven Mauler, which makes each equip onto it cheaper.
Mixing up the Smaugs. The set has three Smaug creatures. Smaug, the Great Calamity // Spew Flame is a common , a 5-mana removal spell (5 damage) that later becomes a 7-mana 5/5 . Smaug the Magnificent is a mythic 4-mana 4/3 flier with that makes a in each of your upkeeps. Both are mono-red. The third, Smaug, Wicked Worm, is black and red, so this deck can't cast it.
Cardsplain