Army of Ruin

It seems easy if you read the discription but it was abit tricky for me,especially since i already had like 600 000 gold spend on upgrades,so i had to reset everything,then what i dit was,is i spend 1 point(100gold) on xp,vacuum,fireate and the rest on dmg,was playing with Ariana and i used her because she builds up damage and her ability helps when she is overwhelmed
I used Toxic Stench,Wolf's Fang,her spears & Volcanic orbs,Since her spear only do damage to enemies infront of her did not rely on it so much i only upgraded Wolf's fang and Toxic Stench