New Mythic Event Chest pull rates (odds fetched from Taran's World)
Odds were previously identical to Gem keys, now they are slightly higher
1 Chest: 0.096% -> 0.104%
50 Chests: 4.69% -> 5.07%
500 Chests: 38.14% -> 40.56%
New Legendary Event Chest pull rates (odds fetched from Taran's World)
Odds were previously identical to Gem keys, now they are slightly higher
1 Chest: 2.000% -> 3.200%
50 Chests: 63.58% -> 80.33%
500 Chests: 99.99589760% -> 99.99999133% (this is just for fun, you were basically guaranteed a legendary in 500 chests anyway)
TL;dr People trying to pull new Legendaries will feel the difference, and it is a very positive one. In comparision, the gain in Mythic odds is very slight.
Depends on what kind of calculation you are looking for.
A legendary chance of 3.2% means you’ll on average need to open 100/3.2 = 31,25 chests to pull a legendary. Assuming you buy in bulk, 50 event keys cost (50 * 15) * 0.9 = 675 gems. That makes the average cost 675 * (31.25 / 50) = 421.875 gems. If you intend to pull a specific out of several available legendaries you need to multiply that amount with the number of available legendaries.
Just to stress it again, this is about averages, meaning that spending 421875 gems this way will on average grant 1000 legendaries, give or take a few. Pulling just the one legendary you want may take quite a bit less/more gems, depending on how lucky/unlucky you get.
A legendary chance of 2.0% means you’ll on average need to open 100/2.0 = 50.00 chests to pull a legendary. Assuming you buy in bulk, 50 Gem keys cost 450 Gems. That makes the average cost 450 * (50/50) = 450 Gems.
This means that if you are looking to just pull Legendaries (say you are a new player), it is actually CHEAPER now to pull from Event Keys than from Gem Keys.
Odd side note, you mix and match using periods and commas for decimal separators.
EDIT: Did the math on Mythics and its 9375 Gems in Gem Keys per Mythic and 12980 Gems in Event Keys per Mythic. Increased odds outweigh increased costs but only for Legendaries, Mythics aren’t worth pursuing unless you have the Event Keys on hand already.
Biggest difference is that event chest pools tend to be kingdom based. Most kingdoms have 1-2 legendaries. So the chance to pull the one you want is huge comparing with gem keys.
Even when event chests are race coded, a certain troopntypenhas far few legendaries in the pool than the more general gem key pool.
Same goes for mythics. While it may be cheaper to pull A mythic from gem keys than event keys, that successfull pull chance has a second roll attached, between the avalaible mythics in the pool.
While event ley mythic pool is usually 1-3, gem key mythic pool is far bigger. Far bigger chance to get an owned/useless mythic (Gargantaur anyone?).