News: 2 players got warning.
Challenges period: 2018.12.12 Maintenance - 2019.01.03 09:00
Archer's Seal period: 2018.12.12 Maintenance - 2019.01.09 Maintenance
Unofficial Note: Although it is not stated on the event page at the moment - there will be continuation of archer challenges for 56,57,58 lvls starting from 2018.12.19 Maintenance - 2019.01.16. Unless there were some changes to the challenges that I've missed - you will need to lvlup your Archer in order to achieve them, so I would not recommend to rush for the lvl 60+ prior to 2018.12.19 Maintenance.
Part I: 2018.12.12 Maintenance - 2018.12.19 Maintenance
Part II: 2018.12.19 Maintenance - 2018.12.26 Maintenance
Period: 2018.12.12 Maintenance - 2018.12.19 Maintenance
Period: 2018.12.12 Maintenance - 2019.01.09 Maintenance
Combat EXP +100%
Skill EXP +30%
Changes
Package sale period: 2018.12.12 Maintenance - 2018.12.19 Maintenance
Sale period: 2018.12.12 Maintenance - 2018.12.26 Maintenance