The cost of a creature as determined by PhantomFox's research is equal to the Attack + HP Value + Skill Value + Other Modifiers + Elemental Bonus
HP Value
0 [-1]
1-5 [ 0]
6-7 [+1]
8-9 [+2]
10+ [+3]
The skills are valued at
+1: Gravity Pull, Infection, Vampire, Stone Form, Lobotomize, Lycanthropy, Evolve, and Phoenix’s rebirth
+2: Devour, Paradox, Mutate, Poison, Dive, Heal, Immortality and the status effect, Devourer’s quanta drain passive effect, and Freeze
+3: Hatch adds three quanta to the cost, and growth abilities are also worth three
+4: Spawning
"Lastly, an ability that generates quanta adds one quanta of cost for each quanta generated. Firefly has one extra quanta of cost, but Rustler adds two."
Other Modifiers
If the skill requires another type of quanta from the creature [-1]
If the skill requires sacrifice of the creature [-1]
Elemental Bonus (all these bonuses are free)
Fire creatures gain +1Atk
Life, Light, Air creatures gain -1Cost
Gravity creatures gain +1HP
I made a mistake in the calculations above I forgot the +3 cost of Devour's growth side effect
The equations should be
Emerald Tiger
2 [Atk] -1 [Life Bonus] +5 [Devour and Both Stats Grow] * .5 [Chance Sucess] -1 [Duo cost] +1 [Devour outside of Gravity]
=3.5
round to 4
Elite Emerald Tiger
3 [Atk] -1 [Life Bonus] +5 [Devour and Both Stats Grow] * .65 [Chance Sucess] -1 [Duo cost] +1 [Devour outside of Gravity] -2 [Max upgraded bonus]
=3.25
round to 4