Here is the full list of all 33 HERO DEFENSE achievements.
Hit at least 20 creeps with a single poison spell
Have Barrows slow at least 20 creeps with a single attack
Kill 500 Creeps with Spells
Kill a creep that is slowed, poisoned, burning, cursed, scared and cut by razor splinters at the same time
Defeat the Ghost Pumpkin.
Kill any boss using only Angry Mobs
Charge a character to level 10
Defeat Count Necrosis
Defeat Alana Nightshade
Defeat Redfang Wrathborn
Unlock Wylde
Defeat the Queen of Corpses
Unlock Jane Doe
Defeat Dr. Amalgam
Unlock Sam Hain
Survive your first encounter with Count Necrosis
Reach the Village
Defeat Bones O'Malley
Unlock Barrows
Kill 50,000 Creeps
Fully upgrade the Village
Upgrade every weapon to the highest level
Defeat Count Necrosis, once and for all
Have Jack shoot 10 bolts at once
Have all heroes do their Hero's Strike at the same time
Win a map on Insane difficulty with 100% Early Called waves
Have at least one rune of each type
Complete the "Tower Defense" challenge on Insane difficulty on any map
Complete the "Border Warden" challenge on Insane difficulty on any map
Complete the "Coast Guard" challenge on Insane difficulty on any map
Watch the credits to the end
Gather all stars on all maps.
Defeat over 100 waves in the Endless Mode.