Build in the showcase(credit to Loser Fai of youtube), the average Lv of the build is just 16 in this video :

Rend Blackhand Lv 16 – No talent
Vulture Lv 13 – Feeding Frenzy
Fire Elemental Lv17 – Immolation Aura
Whelp Eggs Lv17 – Dark Iron Armaments
Stonehoof Tauren Lv 16 – Momentum
Whelp Eggs Lv 18 – Flame Burst
Harpies Lv18 – Infectious Swipes

Notes :
1.Whelps eggs are deployed at the spawn location of the Meat Wagon to damage them as soon as possible, Meat Wagon is bombard which can’t target the dragons.

2. Most of the enemies are bombard(can’t attack flying units), that’s why most of the minis in the video are flying units.