Max HP possible is 500
Current max possible Jelly base stats are:
Unupped: 499/8|1+499/6 = 62|84
Upgraded: 499/6|1+499/5 = 83|100
However these stats require heavy usage of 
for Stoneskin and probably the new Shard of Sacrifice to be stable at 1hp for a couple of turns.
*whistles* that is a strong creature but it would require a lot of set up like you said, so is the recommendation to decrease the growth rate or keep it the same?
I made no comment. I did not say if it was UP, Balanced or OP. However it does need to cost more than 3
Would it be to a player's advantage for part of the cost is damage to that player?
Seconded.
I suggest changing the stat formula to be more similar to Catapult
[Constant] * ([Max Hp] - [Current Hp]) / ([Constant] + [Max Hp] - [Current Hp]) Rounded down
This would have a max of [Constant]
| loss Hp | Value |
| 10hp | 0.50*Constant |
| 20hp | 0.67*Constant |
| 30hp | 0.75*Constant |
| 40hp | 0.80*Constant |
| 50hp | 0.83*Constant |
| 60hp | 0.86*Constant |
| 70hp | 0.88*Constant |
| 80hp | 0.89*Constant |
| 90hp | 0.90*Constant |
For example of [Constant]=15 then the values for every 10 hp loss would be [7,10,11,12,12,12,13,13,13]
With this system I would recommend a cost of 10hp as part of the cost.
Alternatively it could deal some damage to its controller per turn.
