Selling creatures is your main source of gold. You can sell your creatures and boosters twice as expensive on Wednesday and Sunday (event starts at 11:00 UTC/GMT +3)
Cost of sales of the creatures grows in accordance with their elite. e.g. you can sell nonelite grade I lvl 1 creature for 8000 gold, but the same creature with elite status will cost: 8000 * 1,3 = 10 400 gold.
Important note! Before selling your creatures upgrade them on megaevolve days.
Cost of sales of the creatures grows in accordance with their level. Maxed level creature costs twice as expensive as one level creature (It does not apply to hybrids). So don't sell your not upgraded creatures unless your army is full.
T1 and T2 elite creatures can be favorably sell with grade IV. But if you have difficulties with its evolution (you miscount evo materials or additioanl creatures or shadows etc.) you can sell T1 and T2 creatures with grade III and even II. Nonelite T1 and T2 creatures can be favorably sell with grade II.
Cost of nonelite 1 level creatures (on Megasell day and fully upgraded 4 times as expensive):
Grade I — 4000 gold.
Grade II — 16000 gold.
Grade III — 36 000 gold.
Grade IV — 64 000 gold.
Grade V — 100 000 gold.
Grade VI — 144 000 gold.
Grade VII — 392 000 gold.
(It is difficult to find VII+ nonelite creature unless someone wasted lots of time and gold on evolution)
Cost of leveled up elite creatures on Megasell day:
T1 grade II — 112 000 gold.
T2 grade II — 83 200 gold.
T1 grade III — 424 800 gold.
T2 grade III — 252 000 gold.
T1 grade IV — 1 369 600 gold.
T2 grade IV — 755 200 gold.
T2 grade VI — 5 846 400 gold.
There is a rumor that favorably to sell T2 grade VI creatures. But before sell them you should upgrade them in case of having grade V creatures (which is not favorable to sell). In case of having 4 T2 grade IV creatures and 3 T1 grade III creatures (which is needed to evolve to grade VI) taking into account the evolution cost and shadows fuse it is favorable to evolve 2 identical T1 grade III creatures to grade IV and sell 5 grade IV creatures.
Cost of hybrids (+30%):
Grade IV — 52 000 gold (without Megasell event)
Grade VII — 104 000 gold (without Megasell event)
Imoprtant note! DO NOT SELL your evo materials, shadows and fruits! Their cost is very low and you shouldn't sell them even if you are very low on gold. Better sell boosters.