I was struggling with this, especially wanted the name to join up. Unfortunately, I'd have to sacrifice the card art, cause it was losing focus. A shame, but as a designer, this was my design decision.
Combining stats is just through addition. Attack 2 creature + Attack 2 creature is Attack 4. Slowly, the process goes like: See the left half's Attack, see if any effects affect it as a half, put that amount of dice on top and do it on the other. Finally, check if any effects affect it as a whole and add dice to that. Say that it ends with 5 dice? Then roll 5 dice. For defense, no rolls though, so no dice, just count em'. Shouldn't be that hard.
The style will be cute quirky and creepy, yes. Creatures won't be just the typical ones, I'll go insane and make ice cream people, cacti on fire, chinese take out noodle octopi, you get the picture.
The numbers were placeholders really, I really didn't think about what I put on it. Since defense is basically health, a defense of 0 means on the next turn he dies. There won't be a lot of defense 0 creatures, but there are some that even utilizes this disadvantage by being a cheap donk. Medium attack, zero cost, zero defense, can't be fused, almost like sending a bomb to be exploded then discarded.
I'm lovin' this feedback, if you have more do tell, I need to know people's concerns to fix this.
As I said, this was primarily for me making card designs & illustrations, BUT it'd be worth ten times more if it's playable, and a longshot but possible HUNDRED times better if I sell it.