Ok, I am far away to be some expert or anything similar, but here my 2 cents about balance changes:
Defiant Hunter -> Make it 6/6
Docile Panda -. Make it 5/16
Granthar -> Make it kill character in command too.
Rabbid Rabbit -> Make it transform in a 4/4 Bloodthirst 2 Beat Zombie.
Ancient Agression Emblem -> Increase the deploy cost and the ability cost 3, but make it being able to target your own characters
Cottontail -> Reduce the ability cost to 2, if it this make him too cost effective change his stats to 20/20 and cost to 10, this way he will be a late game card and this mitigate the cost efficience agains rush and agro.
Genesis Spy-> Increse the number of "Misinformation" placed on the deck to 4, or maybe 5 at max, but make it has the followoing effect "Pay 4, draw a card".
Kinectly Overload Drone -> make it 1/1 OR reduce its cost to 0.
Mechanics Overseer-> Increase the cost to 5, reduce the stats to 5/5, but make the buff +2/+2
Angelify -> Increase the buff to +5/+5 or reduce the cost to 4.
Tinker -> Make it triple purit, but increase the buff to +2/+2
Dragon Project-> Make it has the following effect "Pay X, exaust, for each 1 resource spent, Dragon project becomes 10% complete, when it is 100% complete, it creates a 30/30 Flying Unstopabble machine Dragon. If the card would become too strong you can reduce the dragon´s stats to 20/20.
Orion Grave -> Make the reduce cost buff being able to play characters with 0 cost.
Imolation Drone -> Reduce the cost to 2, make it 1/1 with Flying and Imolate and keep the 1 damage effect.
Aleta Imortal Sorceres -> Reduce teh ability cost to 3.
Apparition -> Reduce the cost to 5.
Brute Spawn -> Reduce the stats to 1/1, increase the cost to 5 and make the bonus be +1/+1
Groteske brute -> Make it only be forbiden to block if the ability was activated and reduce the ability cost to 3, or 4 at max.
Verore Death Workship -> Increase the initial stats to 3/3.
Veorian hidra -> Make the buff be +1/+2.
Death Blast -> Dont remove any character from the graveyard, but for each CARD in your graveyard deal 1 damage to your opponent fortress.
Heat Wave -> Increase the damage to 3.
Aberion, The hammer of Dawn-> make he cost X and its stats be X/X
Duelist -> Make it 5/4, or 4/4 at least.
Frontline Warrior -> Make the buff be +1/+1. If this makes it be too strong change the buff to only activated while deployed to while is ob the battlefield or the Defese Zone
Kali Ascended -> make it 10/10.
klore -> Reduce the initial stats to 1/1.
Mark 1 Brimstone Battletank -> Reduce the ability cost to 4. if this is too strong make the ability only be playable while deployed.
Tithe Collector-> Reduce the status to 0/1 and the cost to 3.
Vicious Ranseker -> make it 6/6
BloodBath -> Reduce the cost to 5.
Call the Cruze -> Remove the assault zone lock, reduce the cost to 3, but create three 3/3 characters, if this would make the card too strong, still reduce the cost to 3 and remove the lock, but create three 1/1 characters.
Exaust -> Reduce the cost to 2.
Bromich banner -> Reduce the cost to 3.
Brimstone -> Reduce the cost to 2.
DESCENDENTS OF THE DRAGONS
Chef -> Increase the cost to 3, but make it buff itself.
Avatar of Lingao-> Attack a enemy fortreess deal damage as morale AND as health. If he becomes too strong reduce the stats to 12/12 or even 10/10.
Echo of the Batlefield -> Increase the stats to 7/7, or at least 6/6.
Soldier of the Wall -> Make it 6/7.
Disarm -> increase the csot to 3, or even 4, but make the effect be forever.
Humble -> Dont heal the enemy character when used, damage will not count as a "debuff".
Jinhai Ambush -> Reduce teh csot to 3, if this would make the card to effective just make it create three 1/1 characters.
Suprise Deffense -> Increase the cost to 5, and would die, instead it goes to the support zone and be exausted for 3 turns.
Heavens Bell -> Make you be able to choose the position of the card in the Defense Zone.
Shift Stone-> Increase the csot to 3, or even 4, but the effect lasts forever.
Counting the Days-> Make a complete rework, I suggest making it Triple Purit the following effect "On the first turn if Counting the Days is on your hand or deck its automatically played for free, at the end of each turn its become 4% more complete, at the end of teh turn, if Counting The Days is 100% complete, you win the game"
SLEEPERS OF AVARRACH
Cyber Infested Dragon -> Increase its stats to 20/20, but remove the Endless Hord effect and the auto exile effect. Add teh folowwing effect "If Cyber Infested Dragon comes to the battlefield from the graveyard its stats are 15/15 (or 12/12)"
Zombie Scavengeer -> Reduce its stats to 1/1.
Overwhelming Dead -> Increase the cost to 5.
Endless Horde -. increase its stats to 6/6.
Undeath Wish -> Make you be able to ressurect a enemy character too.
Demonborn -> Makes its initial status 1/1, but remove his ability and give him Flyingas a passive OR Remove his abiliyy, give him Flying as a passive, increase the stats to 5/5 and the cost to 3.
Demon Gambler -> Reworkteh card, make the initial status 4/4 and give it the folowing effect "Demon Gambler enters the field with one "Coin Counter", while he has a "Coin Counter" he receives a +3/+3 buff (initial stats + coin buff= 7/7 character). Remove a "Coin Counter", Demon Gambler has 50% of chance to reveive a adittional +3/+3 buff and 50% of chance to receive a -3/-3 debuff (initial stats + the loss of the passive coin buff + the loss of the gamble= 1/1 character).
Gravedredge Demon -. Make it 12/12 and reduce the cost to 5.
Hungry Devil -> make it 9/9.
Infected Devil -> make it 7/7
Gatherer the Weak-> Increase the cost to 3, give it exile 0.
Demonize -> Remove the "Consume 2" effect.
Rework the "Champion Rule" to make you be able to have any number of champions deployed, but only ONE COPY of each champion on your deck.
Gathering Thoughts-. Remove the auto exile effect.
The Calamity -> I have two suggestions for this polemic card 1) Make it only activated at the end of the turn its played, in other word, a soft nerf. 2) Reduce the cost to 10, but you can only have ONE Calamity in you deck and Calamity auto exile after used, in other words it becomes a one use per game card, no more recicles Calamities, this will be a total rework.