This event has changed from being one of the best to being extremely lackluster.
You can't plan anything except the new shrine. In the christmas event you could at least save up enough to be fairly sure to get what you wanted. Here, it is 20% chance per chest (if you buy the gold one) to get the daily special (if the wiki is correct).
Some math to illustrate:
Lets say you manage to get five gold chests (600 eggs). At 20% (1 in 5) chance that is sure to get you one of the daily special, right? Wrong.
The chance of getting at least one daily special using five gold chests is
Code:
1-(1-0,2)^5 = 1-(0,8)^5 = 1-0,3276 = 0,67232 = 67,2%
That is, 1 minus the chance of not getting the daily special five times in a row. Or put another way, the chance to not get nothing.
So if you have 10.000 people buying 5 gold chests each to get the daily special, 3276 of them will not get even a single daily special.
It is actually a bit more complicated because you do have a chance to win eggs as well, allowing further chest attempts.
So the expected value E (measured in daily specials) of a gold chest is first 20% chance to get the building straight away, then 5% chance to get 250 eggs which is 2,08 new gold chests, and lastly 17% chance to get 150 eggs which is 1,25 new gold chests. Each of the new chests have the expected value E as well, so we can solve for E.
Code:
E = 0,2*1 + 0,05*(250/120)*E + 0,17*(150/120)*E
E = 0,2 + 0,1*E + 0,2*E
E = 0,2 + 0,3*E
0,7*E = 0,2
E = 0,2/0,7
E = 0,286
The chance to open five gold chests and getting at least one daily special is (using the calculated expected value):
Code:
1-(1-0,286)^10 = 1-(0,714)^5 = 1-0,186 = 0,814 = 81,4%
So it's a bit better, but still a terrible way to do rewards. RNG is always terrible. At least have a hard-ish cap on how many times you can fail, like the christmas event.
Out of 10.000 players that buy 5 gold chests to get that daily special they really want, over 1800 players will not get a single one.