I have a few good ideas but i dont know anything about pixel art and I dont have the suitable programs either so u might have to make it urself, anyway they are still from minecraft so they should be easy to make for u, here are the ideas:
TNT Type: Trap
When this card is faced up, destroy 2 resources of every type from ur opponent and destroy 1 resource on every type from urself. Then remove this card from the game
Pickaxe Type: Special
When this card is faced up, you collect a rare ore at the start of your every turn and lose stone
Strength potion: Special
Two of your mobs will have a 300 attack increase for 2 rounds when this card is used
Ghast tear Type: special
All of your mobs regenerate 250 health for a consecutive 3 rounds
Cave spider Type: Wild
500 attack, 500 defense
When battling another mob, the opponent's mob's defense will decrease by 200 every round until 2 rounds had past
Cake Type: Special
Gives 3-6 monsters a total of 2000 health, and is then removed from game
Cobweb Type: Trap
The mob that has been targeted will have a decrease of 400 attack and defensive power for 2 rounds
Steve Type: Normal
2000 attack, 2000 defense
This mob is able to attack as many mobs as he wants
Hope to see this game soon Sabretooth!