First redeem of the event will yield you 10 Mira EEs

The Success Chance is

1st Start = 60%
2nd Star = 55%
3rd Star = 50%
4th Star = 40%
5th Star = 30%
6th Star = 20%
7th Star = 19%
8th Star = 18%
9th Star = 17%
10th Star = 16%
11th Star = 14%
12th Star = 12%
13th Star = 10%

Between the times 2-4PM KST on the dates 22-27 the Success Rates on Mira EE are doubled

120, 110, 100%
So the first 3 can be used with an 100% pass rate.

These Mira EE can be used on equips with slots still.

You can buy 1 Mira EE in Winter Shop for 10 coins or 3 for 25 coins.

They also added Innocent Scroll 60% in Winter Shop "you get one free every day?"

Innocent Scrolls do not reset Potentials or Reset equips that were discovered with Additional Options.
"Which means Equips that were Flamed to get Additional Options will be reset"
Mira EE can drop from bosses but not at a 100% Chance.

Abuse this event. "Also you cannot use Mira EE on Superior Equips I tried... that would be op anyway"