Best cards:
(I will add the mana cost too)
Minotaur for damage and speed (10 mana)
Unstable Potion + any weak monster (bat is the best option because of its vampirism) [6-7 mana(5 for the unstable potion and 1-2 for the monster)]
Fairy next to you for +1 hp per turn which is useful for spark mage and not drawing any cards damage (1 mana)
Summon Totem (3 mana) (will summon one of these 3 totems only)
-Fire Totem: snipe enemies that may cause problems (for example all the ratfolks that build things)
-Heal Totem: healing random allies
-Buff Totem: adding damage to random allies (well paired with fire totem)
Smite for sniping any enemies that may cause problems
Blacksmith and Innkeeper for adding cards that are pretty useful and prevent you from getting card damage for longer (3 mana for either one)
Snake is good for its deathtouch although you will need to keep it out of enemy monsters range and protect it. (1 mana)
Cards to NOT get:
Spider because too slow and other weak monsters cost less mana (2 mana)
Hell Critter because even though it costs 0 mana it does no damage so it's only useful as a decoy and there are always better weak monsters for decoys (0 mana)
Beast simply because Minotaur is better (8 mana)
Goblin because the other weak monsters have effects like vampirism and swarm while it has nothing but base stats (but at least has 2 hp so it's somewhat useful for spark mage) like Hell Critter which is another reason not to get Hell Critter (1 mana)
Bonus Fact: if the death touch snake gets to the other mage and attacks, the death touch doesn't work.