But on the question if the drop rate is pathetic or not - I guess even if you optimize everything for the event (I read somewhere that for breeding/hatching it's best to breed only Thunder Eagles), you'll have to spend gems to get the last monster.
I always had full points in PvP fighting and the other fights, but was hatching/breeding normally (trying to get some breedable legendaries). I had to spend about 100 diamonds to speed up getting the first 4 monsters. Megaosteum is within reach now (288 diamonds left), getting Vodyanoy could be tough, Baba Yaga is out of reach unless I spent a lot of diamonds.
I wonder, is it known how the price of the monsters is calculated depending on the completion of parts? Has someone tried to make a timetable how to get through the island with minimal cost? Obviously I should have optimized my breeding for the event, which would have given me some speedup or saved me a few diamonds. Say, I want to get Baba Yaga in the end. The diamond cost for the monsters drops in a nonlinear way, so it's obviously a bad strategy to just collect until the remaining price is really low (say 30 diamonds or less), because this will take too long and I'll end up where I am now, with Baba Yaga out of reach.
OK, 7 monsters, 10 days. Would it be fair to assume that the cost is increasing throughout the island, and the "optimal" strategy to get to the end would be to buy the monsters after a fixed time? Say, buy the first monster after 24 hours, the next monster after 30 hours, and so on, giving the highest amount of time to Baba Yaga (maybe 48 hours). Is it possible to estimate the number of diamonds to get there? My guess the answer would be "too high" for me as I'm not a whale, but I could probably aim to get 6 out of 7 monsters.
On a related question, for a fixed monster, does it make sense to spend items on single tokens (the objects you collect over time), or should I just collect until the diamond cost is acceptable?
My bottlenecks are currently gold and breeding. I'm 12 of 14 in PvP combat (85%), 6 of 11 in breeding (54%), 29 of 42 in feeding (69%) and 45/77 in gold collecting (58%). So obviously PvP will be completed well before any of the other tasks, with gold collecting probably coming up last. (Breeding seems to be pretty random whether I get an item or not, I had cases where I bred an epic monster after 24 hours and did not get any tokens , while I bred a Pandaken and got one. But I guess if I focus on shorter breeding times that should catch up to gold.) Does it make any sense to spend 3 diamonds for a breeding token or a few of diamonds to buy steps in the gold collecting parts?