That is a totally different card idea, and would be roughly equivalent to a Deja Vu that could continue copying itself indefinitely - without limits of field space. I think you underestimate the potential of exponential growth. Let's look at some numbers in a simple
deck with Gravity mark:
Turn 1 draw unupped Earthchild, upped Momentum, at least one Earth tower, play all = 1 damage total.
Turn 2 double Earthchild now 2|4 = 3 damage total.
Turn 3 double Earthchild now 4|8 = 7 damage total.
Turn 4 double Earthchild now 8|16 = 15 damage total.
Turn 5 double Earthchild now 16|32 = 31 damage total.
Turn 6 double Earthchild now 32|64 = 63 damage total.
Turn 7 double Earthchild now 64|128 = 127 damage total, win.
...
Turn 8 128|256
Turn 9 256|512
Turn 10 512|1024
Turn 11 1024|2048
Turn 12 2048|4096
Turn 13 4096|8192
Turn 14 8192|16,384
Turn 15 16,384|32,768
Half a stall game later it's in the tens of thousands.
That is with the smallest possible attack buff, a reasonable draw, and ONLY using Earthchild. After turn 7, it is capable of dealing a one-hit kill by itself. (Did I mention this test lets it ignore shields?) Throw in multiple Earthchildren, a bigger starting buff like Blessing or mildly lucky Chaos Power, some Earth stall cards like Basilisk Blood and Diamond Shield, not to mention GRAVITY PULL, and you have yourself something exponentially more powerful than Growth.
It's like the age-old experiment: if you're paid a penny on the first day, and your pay doubles every day for a month, you'll be a millionaire.
